For both 912lancelot and David1k and others whom may be interested,
I would just Very clean them as long as they either 'humm' our you have continuity with the wires. the motor cover should just 'pop off' with a carefully placed small screwdriver blade revealing the stator windings and the rotor; since the pictures didn't show a side shot I believe the motor cover is just 'snapped' in place and should come off with care.. Keeping the wire insulation out of the way, Hand clean with a small brush and Ultrasonic cleaning fluid and carefully blow dry with canned air. It may take a couple of times to remove all the 'gummy' 50 plus year old lubricant.
As for the gear case, do not try and disassembly it unless absolutely necessary because, from my experience with a similar motor, the reduction gear shafts are mounted in two very thin Micarta plates that are very brittle and if mishandled would break. From the picture I believe the hole in the cover place is the key in that all your gear cleaning will be through that hole. As you did with the motor, use the Ultrasonic cleaning fluid, but use a syringe or an eye dropper, and insert one or two syringe or an eye dropper full into the gear case. Put your finger over the hole and carefully shake the unit for a few minutes and then drain the fluid. It most likely will take several times before the old lubricant will dissolve and flush out.
To test for your success, connect the two motor leads to a power source and the drive gear should turn. Due to the gear train gearing you Cannot turn the drive gear and expect it to rotate. However, and with the power Disconnected, you could very carefully rotate the rotor, then the drive system is in the proper sequence and you should see drive gear rotate. Remember, drive gear RPM is very low. one or two RPM's, so I slip marked (black marking pen) the drive gear to check for rotation.
The unit should work as per the previous paragraph describes?? I would again clean the gear case several more times and then carefully blow dry with canned air. Since I do not know the motor orientation when mounted, but would guess that the hole is 'up' whereas the lubricant won't run out I would use clock oil to lubricate; the unit does not need to be filled to the bottom of the hole because as the gears turn they will self-lubricate the gear above by the oil being carried by the gear teeth. Remember, an 'heavy' lubricant will slow down the motor due to the viscosity of the lubricant.
As a note - you may find the ancient lubricant doesn't easily dissolve/remove with Ultrasonic cleaning fluid, the only other cleaning fluid I know of that does is car gas which brings up a Few safety concerns. Some of the other members may have a different suggestion, but I have found few that work with fully dissolving old grease. 91% Isopropyl Alcohol kinda does, but the task is to remove 'all' from the gears. For the most part, old grease in the 'corners' doesn't effect the gears turning.
As an aside, I found at least two clock motor repair 'sites' on the web by Goggl'ng 'electric clock motor repair' or something similar. That is for both similar clock motors as pictured or the round motors "GE" style; GE bought out the original company back in the 1930's if I remember correctly. My information is on my other computer of which is not accessible at the moment. lol
I do hope the above comments are useful.
Regards,
A Novice