The starter on our 1950 UTU will barely turn the engine over now, just groans, that happened suddenly. I've been starting it with 12 volts but it hasn't been used much for a year or two. I was going to switch starters with one off a 51 parts tractor we have. It spins great so I put it on but soon discovered that the gear is smaller and it doesn't touch the flywheel. I tried to change the drive from one to the other but I don't know if that is possible either, the bendix is totally different so I put the one that fit into the housing of the good one to try but it must be an armature issue because that barely spins too. Any ideas if the drives could be interchanged or does anyone have one for sale with the larger gear setup.