We really need the Make and Model of the A/C you are repairing. This happened to me with a Coleman Mach 15. I could get the motor to run, but once it stopped for any reason it wouldn't start again. Dismantled the motor, cleaned the bearing sleeves, polished the shaft, reassembled. It STILL would not re-start after it'd been run. I was oiling it with Turbine Oil, meant for motors in appliances.
Westend - Crazy thing - It'd free up, and run longer, if I sprayed WD-40 instead of applying Turbine Oil. I know the stuff goes away fast, but it was actually more effective than the right product.
OP - IF it's Coleman, you should be able to get the fan off the long end of the shaft. Or, push it all the way to the motor. Then the motor, with a piece of the blower housing attached, and squirrel cage still on it, will come out of the housing. On ours, that housing was foam lined.
If you have a Dometic or other product, I can't help much. I remember that many of their newer models are extensively plastic, foam, space age stuff.