Throttle Lever Problem on Farmall M

I'm slowly addressing the many problems with an old 1951 Farmall M Tractor. Currently I'm looking at the throttle lever which will not hold it's position at higher settings. Setting the throttle anywhere from minimum to about 1/3 works fine but at higher settings it jumps back to a lower setting the first time I hit a bump. I did notice the lever seems to be under considerably greater tension at the higher settings. Also, there is some "wobble" in the lever itself. Before I tear into it, wanted to see if anyone had any suggestions as to what I should be looking form.

You can take the whole assembly apart and its pretty apparant how it works. My spring was broken so a trip to Westlakes found a suitable replacement.

Then I put a spot of weld on the lever and using a file put a new edge on it.

Mine has sawtoothed shaped notches. Some I have seen are square notches.

Finally, I had some wear in the post area. I found that a .40 caliber pistol case was the right diameter. I cut the head off and used the brass case for a bushing.

Cleaned it all up, painted it and it works like new.

Good luck,, Gene

It's normal for the tension to get tighter as the throttle is opened. That is the governor springs doing their job.

You need a good tooth on the throttle lever and good clean notches in the "hat" on top of the steering post. Most of the time the little tooth is worn from previous drivers "ratcheting" the throttle instead of pulling the lever clear of the hat before moving it.

I did notice you can buy the pin that has a nut that bolts threw the handle and also the top cap. But I did what GeneMO did. I used a brass rod to build it up. I had also some worn teeth on the cap so I used dremel with a small cutting wheel to square them up.

Also, if your tension spring has gone soft, you can shim it with an appropriate size washer to give the lever more "bite" into the notches.
mike

Yesterday I repaired my Model 200 with the same problem. I used a dremel tool to shape the notches better. Just go slow and look it over as you work. I disassembled the lever assembly, replaced the spring and cotter pins.
My lever had worn down so much that it had a grove worn in the part which should fit in the notches. I was using a wire to hold it in place. I welded (mig) to the handle and then shaped it with a small grinder. This worked fine. Upon complete reassembly it works like a new lever. Good luck and may the good lord take a liken" to ya"

Thanks to all of you guys for your response to my throttle lever problem. After reading your suggestions I did a visual check and think I see where the problem is. Mine has square notches on the fixed throttle plate (rather than saw tooth) and a rectangular cog on the throttle arm, which is designed to engage these notches. I found the cog is badly worn in the center where it engages the notches. Also, the leading edge of the notches are rounded where the cog rests against them - either due to the throttle lever slipping or being pushed to a lower speed setting. Hence the cog can no longer get a good "bite" into the throttle plate notches.
I noticed the "cog" is a replaceable part, so does anyone know where I might order one without buying the whole "kit and caboodle"? If not, guess I'll have to build it up with weld and grind it to the original shape to fit the notches as several of you suggested. Also, where the front edges of the notches are rounded off may need to be "squared up" as someone suggested. However, that will increase the width of the notches so I may do that only if needed. If these two measures don't totally fix the problem, then I may need to address the vertical play in the lever, estimated to be about 1/2 to 3/4 inch, and could be due to a worn bushing and/or weak spring.
Thanks again!