Switch to a higher voltage bulb. The vibrator motor should be fine.
Picking this thread up again, and perhaps a doubting Thomas on the vibrator motor.
I have not run my 3620 much but put it on the track recently to run it as part of a MOW train. It has an 18-volt bulb but at 18 volts for 5 minutes, that whole end of the car and the metal shell for the light are as hot as a firecracker. BTW, it is not the bulb since I tried this with no bulb and the same super-hot result- hence this is due to heat from the vibrator coil.
Seems this level of heat can't be good for this ancient vibrator coil device. Any ideas on cutting the heat / voltage a bit while running in command mode- the track is on Lionel bricks so 18 volts is what it is.