It will be interesting to see what you find. I have the same sign, with motor working (fingers crossed), but when I got it the bulb socket was burned up and needed replacing.
I have an early Motorola color TV sign that had a seized motor when I got it. I was lucky to find a mechanical fit at American Science Surplus (who recently went out of business, and probably went out of stock on the motor years ago anyway).
The replacement is twice the RPM of the original, and still is very slow to my eye and leaves me wondering how the sign was supposed to be eye-catching.
https://www.flickr.com/photos/old_tv...7677353439537/
Good luck!