Well one trouble with that motor was it drill a habit of leaking molly grease out of the transmission onto the commutator and after a period of time would cause the motor to arch and loose power.You could some times clean the motor with LPS contact cleaner and that would fix it.If not then you would need to replace the motor. Hope that helps.Good luck.
Yes that's the fourth generation I believe 1.2 amp hour 4/5 Sub-C Ni-Cad type 1.Hope that helps.Good luck.
Take the motor in one hand and the trans in the other.Place the motor pinion into the gear cluster on the trans.Angel the motor about 12 degrees and lightly push them together as you rotate the motor.What this will do is let the motor pinion find the first gear in the cluster and once it is found allow the pinion to engage each gear on the trans one at a time.Once all the gears are engaged the two half will go together.Hope this helps.Good luck.
I cannot find the model number on my drill..
I'm just guessing, but take look at this link, maybe it's the one you need.
640567-00 Clamshell Set
Try an impact driver and a torch to loosen up the lock tight.
The bolt is a left hand thread.If you cant get the bolt out it will need to be drilled out with a 19/64 drill bit.This size will drill the head of the bolt off and after the chuck is removed leave the stud of the bolt sticking up high enough to grab and remove.Hope that helps Good luck.