Mullen Discovery Part Identification/Sourcing

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Brian Prindle
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Mullen Discovery Part Identification/Sourcing

Post by Brian Prindle »

Hello! I am a couple years into learning pedal steel and am having an issue that I'm hoping someone can help me identify. I'm not sure what the part in the photos is called, but regardless of how hard I tighten the set screw, it doesn't hold tight enough and the left knee up just ends up flopping around. I couldn't find this part on Mullen's website. I reached out to the sales email a couple times but didn't have any luck. I'm handy enough where I should be able to address the issue, but just hoping someone can fill me in a bit on where to go from here. Thanks in advance!
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Dave Meis
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Re: Mullen Discovery Part Identification/Sourcing

Post by Dave Meis »

That's the lever return stop, and since it's mounted to a hex shaft, I'm surprised that it slips.
If the lever is dropping, I'd check the lock nut that attaches it to the lever clevis (where the lever itself is attached to the cross-shaft assembly).
Or... maybe I don't understand the question.
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Jerry Overstreet
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Re: Mullen Discovery Part Identification/Sourcing

Post by Jerry Overstreet »

I was just posting basically the same thing that Dave wrote but he explained it in simpler terms.

If the lever itself is not loose like Dave wrote, then the only other things I can think of without hands on examination would be threads worn out where the screw meets the cross shaft, in the part itself or the set screw.

Does that screw tighten up good? Does it just loosen up with use? Maybe a little more specific info?
It's the same type of part Mullen uses for attaching bell cranks and reversing lever parts which I've never seen any problems like that and would be unusual for a guitar of no more use than yours.
Bobby D. Jones
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Re: Mullen Discovery Part Identification/Sourcing

Post by Bobby D. Jones »

The part in the picture is the knee lever return stop. The set screw does not tighten the stop on the hex cross shaft. It just holds the stop in place.
Loosen the set screw till it will not drag on cross shaft, Or remove the set screw completely. Wiggle the stop back and forth in line with cross shaft, And remove stop from the cross shaft.
DSC01058.JPG
Circled parts are side view of KL stops.
Check the cross shaft slot in the stop carefully, It must be a parallel slot, And slide tight on the cross shaft. The set screw just holds the cross shaft in the slot.
It may take squeezing the slot closed some, With a vice or set of vice grips. So it slides snug on the cross shaft.
Good Luck on this problem, Happy Steelin.
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Jerry Overstreet
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Re: Mullen Discovery Part Identification/Sourcing

Post by Jerry Overstreet »

Have to disagree here. The set screw in the part in question does tighten against the angle of the cross shaft same as the bell crank.
P7171119.JPG
P7171122.JPG
Without the screw yes, it would still might not move forward and back very much but can still wobble side to side. I also suspect something else besides this is causing the problem.
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Bobby D. Jones
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Re: Mullen Discovery Part Identification/Sourcing

Post by Bobby D. Jones »

If the stop is moving on the hex cross rod, And not stopping the rod.
The set screw, Or the hole it is installed in, Have stripped the threads as Jerry Overstreet posted.
The small hook like part that arrow points at in picture, May have been bent. And not gripping the bottom of the cross shaft. When the set screw is tightened down, To hold the stop on the cross shaft.
DSC01058.JPG
Good Luck finding the problem and cure.
Happy Steelin.
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Brian Prindle
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Re: Mullen Discovery Part Identification/Sourcing

Post by Brian Prindle »

Thank you for the replies and help so far! I believe I have diagnosed my issue. I took a knee lever return stop off of another knee lever and put on the one I'm having issues with, and everything worked as it should. After comparing the two, I realized the one I'm having issues with seems bent (see pic), which makes sense because this issue started when I was packing the steel away a month or so ago.

I've done this multiple times so I'm not sure why it bent this time, but nonetheless I've loosened the screw/nut at the knee lever pivot so that this doesn't happen again. I'm not seeing any knee lever return stops on Mullen's website other than in the knee lever kit, hopefully I can get them on the phone soon to clarify if this is something I can purchase from them.
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Jerry Overstreet
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Re: Mullen Discovery Part Identification/Sourcing

Post by Jerry Overstreet »

Knee-Lever-Kit.jpg
Well, this is a good example of why i shouldn't post about things of which I do not know.

It appears from the Mullen site, even though the attachment is the same, that the Discovery uses different bell crank and stop cutouts where I had just willy nilly assumed all the parts are hex same as other models.

This photo from the parts dropdown @ www.mullenguitars.com shows the breakdown of a complete knee lever kit components.

It is clear from your photo what happened to the stop there. I can't speak for the good folks at Mullen but I would imagine you would be able to buy just the replacement part for your guitar. Perhaps include your same photo of that exact part when you place your inquiry or perhaps it could be replaced with a hex mount lever stop used on a pro grade model.

You could try to bend it back but being aluminum it might break off. Might be worth a try if you're gentle.

For a somewhat closer view of the photo, right click, select open in a new tab, click on that button in the header then select zoom button +.
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Dave Meis
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Re: Mullen Discovery Part Identification/Sourcing

Post by Dave Meis »

The original pics show a hex shaft.. I’m assuming the part got rounded off by slipping. I’m glad you got it figured, and good luck with finding your replacement piece! 👍
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Jerry Overstreet
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Re: Mullen Discovery Part Identification/Sourcing

Post by Jerry Overstreet »

True, but if you look at the photo I posted from the Mullen site, the bell cranks and the stop cutouts are more square than hex which seems odd.

The KL hub does appear to be hex to match the cross shaft however.
Last edited by Jerry Overstreet on 21 Jan 2026 8:28 pm, edited 2 times in total.
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Dave Meis
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Re: Mullen Discovery Part Identification/Sourcing

Post by Dave Meis »

It does look square! 😳. I learned something! 👍
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Re: Mullen Discovery Part Identification/Sourcing

Post by Bobby D. Jones »

I learned something too. From Brian's picture of the Discovery lever stop. It is not 1/2 hex shaped like the Mullen Pre Royal Precision I am working on right now. The Discovery KL Stop has rounded corner shape slot. The pictures of Discovery parts on Mullen's Web site, Has the rounded corner slot too.
I also noticed from his first pictures posted. The Discovery does not have the adjustable pedal stop fixtures, Like the PRP guitar I am rebuilding.