There are a couple of bugs I've found with spit roasters.
First, the position you have to stand to turn the roaster appears to be dependent on the orientation of the fireplace, which can be different from the cosmetic location of the crank. My fireplace is in a corner where my fence passes my cabin, and it tries to move me into my cabin when I try to turn the spit.
The second bug partially offsets the first, because if I just leave a carcass on the spit for long enough, it eventually cooks even if I don't turn it and the fireplace isn't ever lit.