This is is what happens to gears when the chassis axle hole becomes excessively worn. The two gears on the left came from a 372 GP7 which I picked up many years ago.
The gear on the left shows that it had been meshing right up into the worm, which over time has worn the teeth to point and reduced the height compared to a new gear on the right. Also the left gear leaning to the right indicates it was not centred under the worm fully. The middle gear also leans slightly to the right but was not far from the centre.
A chassis in this condition will give poor performance, runs slower which means it will be pulling more current which further compounds the problem. You also run the risk of possibly burning out the armature if left like this from extended running.
In some respect the diesel chassis was not one of Gilbert's finest bits of engineering, to be honest they can be a PITA to get running well at times.
