I'd try removing the four screws on top and spinning the fan impeller by and see if the fan will go. If after spinning it by hand it works, pull off the impeller gently with a pair of needle nose and put a drop of light oil on the motor shaft bushing. These bushings come dry from the factory and I've had fans either get noisey or stop altogether, a drop of oil and I have yet to replace the fan. Having said that if the above method doesn't work you can get a replacement fan motor from Lionels parts site, it should unscrew from the smoke unit and unplug from the board. ** While you have the unit open it would be a good time to change the wicking if its hard.