You can just slide it back in, may take a couple of tries. This only works with those that run full engine speed (later 175's and all 200's) as the gear on the others is too large to get out in the first place). Get the timing pin/bolt, line up the one side or the other on the timing mark on the crankshaft and lock it in with the bolt. Then position the alternator armature so that the corresponding set of points is just breaking and the alternator position locking bolt ear is in the approximate correct position (the alternator is close to it's correct rotation). Push the alternator into the hole in the crankcase. This may take some wiggling, light tapping, etc. It helps to have the o-ring oiled or greased. Be careful to not jam the gears together, you may break the fiber gear. As they go together, you need to rotate the armature shaft back and forth a bit to make certain the gear teeth engage. As they engage, the shaft will rotate slightly due to the helical teeth on the gears. It the alignment is wrong, back it out so the gears disengage, modify your starting position and try again. This also works on 350s.
