This page explain how you can fix your Yaesu rotator, if it suddently stop working because of a broken rubber belt.
The rotator indicator will alwas try to dub the bearing of your antenna setting because of a rubberbelt driving the indicator needle and a potmeter shaft, until this potmeter voltage in the controller box will match the potmeter voltage from the rotator unit.
If you are unlucky enough after some years, and this rubber belt will brake and the indicator needle is unable to turn, then you maybe need this fix. You will still hear the motor spinning inside the boks, but nothing happens.
I am not sure if this fix will work on other models then G-600, but I am pretty convinced that all Yaesu models are very similar.
On the pictures below this text, I will show how to fix it.