M starter questions

My M starter is acting up, works, then fails, works again, then fails. Im not sure whats wrong but I am getting really good at taking it off and putting it back on. I did notice one time when I was tighting the posative wire that the stud turned. I tryed the starter and it failed after just having been working on the bench so it has to be related to that posative stud. Could a wire be messed up that connects to the stud or is this a brush issue? How do I take this bugger apart to fix it? I asked at a few of the local shops to see if they can rebuild it and they dont rebuild in house anymore, they send everything out.

Anybody got a link or instructions on how to fix this starter? I tried searching this site as well as google and didnt find anything but somebody has to have done it and taken a few photos to document it.

If the stud turns, you have broken the weld to the field winding.
Take the starter to a repair shop & get it re-attached.

If you can solder, you can fix it. There are 2 copper ribbons which attach to this stud which need soldered back on. The process will be evident once you clean the connection well. Don't leave any foreign material in the connection--keep it clean. Use only rosin core solder. I only use Kester solder. Don't know how these newer lead-free solders work, though.

If it needs the soldering (make sure it is broken before fixing) Then do it, or have it done. Replacing the starter drive with a clutch style drive gear will make a dramatic difference. The reason it might have "failed" each time might have been the drive jamming in the ring gear. Each time you took it out it unjammed and then worked for a while (or not) and jammed again. If the ring gear teeth are toast, and all smashed over on the leading edge, dressing them with a file might help. There will be primary spots where the engine usually stops, so turning the engine will show them in the starter opening. If the teeth on the ring gear have less than 1/2 of the material left, the new drive might not make it better, but it is worth the try. To replace the ring gear requires splitting the tractor in two at the clutch. Best of luck, JimN

Rich, Where are you located? I have a guy in Beloit and a guy in Burlington that can rebuild it for you.
It is around $100 IIRC. The one in Beloit is kind of moody, but really good. If you take it to him you will get the nasty for overtightening the nut. Whatever you do! Don't say, "then why do they put an 11/16ths on it then!?!"

Next time it happens, put the tractor in 5th gear and rock it by pushing on a back tire. It'll usually unstick the drive. It's not a fix to the worn drive or ring gear teeth, but it should free the starter up without having to take it off.

I second the 5th gear trick. Most M's will require this about one every 100 times they are started. Every tractor I have driven seems to do this from time to time.
If it is worn ring gear teeth you can take a flat screwdriver and turn the ring gear to a good spot so the starter will engage. Don't forget, it is even trickier than splitting the tractor to get at it. IIRC you have to put the gear in a fancy oven to expand it and then place it on the flywheel.

Fancy might be Amana, GE or Roper, but not fancy like a lab furnace. Be careful with the owner's feelings.
An Oxy/acetylene torch will do as well. (cut off the old, heat the new evenly all around to about 250 to 300 degrees, and drop it on. JimN

Thanks for the help everybody. Seems I did see the stud turn a little but must not have broken the weld to the field magnets. Everything checked out fine with a meter. The youtube video I found mentioned brushes causing the starter to fail and then work again after tapping on it. That got me to thinking maybe me bumping it around taking the starter off and on the tractor would be enough to make it work again. Turns out, I think that was the problem as the brushes were pretty bad. It was hard to tell because looking in the empty case, everything looked fine but I kinda measured the opening between the brushes after I removed the windings and compaired that to the commutator diameter and there was not much left for brushes.

I didnt have any new brushes so I just filed the edges clean and reinstalled them. Then I polished up the commutator, it was pretty dark with carbon. Put it all back together and it started perfectly. So far its been back together for a week and no problems so I am hoping the problem was the brushes. Now I just have to find someplace that sells a rebuild kit or just brushes, Im pretty sure my fix was a temp fix at best but at least I know what it is and can take it apart in about a hour.

Here is the youtube video I found, it was pretty helpful seeing as how I didnt really know what I was doing and have never disassembled a starter before. I have replaced them but never taken them apart and fixed them.

youtube.com/watch?v=CxjPpytfnv0

Thanks again for the help everybody.