RV Repair: 1977 Coleman Model #4235A Furnace, mud dobber, mud nest

Question
I had to remove the entire assembly to get the blower motor assembly out due to a massive hornet/mud dobber mud nest caked inside. The problem is that I cannot get the retaining piece off of the blower motor shaft to remove from the squirrel cage, even with set screw out, to replace the motor. Using a brass drift, I have moved the shaft down until it even with the retainer, but cannot get any further. Please help with any suggestions, and where can I get a new motor? I have sprayed the shaft with penetrating spray with no luck. Also, this is a 1977 Concord Class A motorhome. How do you get to the defrost/heater blower motor? We have taken out every screw we can see, and still can't get to it! Any advice would be appreciated! We are slowly ressurecting this beast!

Answer
Hi Donald,
 As far as the squirrel cage goes, you are going about it exactly right, Maybe try having someone hold the squirrel cage and strike the shaft with a heavy hammer on the brass drift. The hanging  weight of the of the motor may help. The two metals rust together. There is no easy way.
 I have never worked on a Concord, so I am not much help. RV manufactures love to hide screws. I don't know. You may have to cut an access and make a good looking cover to hide it.
 Sorry I am not more help. Good Luck.