I work for Crown and we always replace the drive unit with a new or remanufactured one instead of rebuilding them. My boss don't allow us to rebuild them. Not cost effective, even for our full maintenance accounts where we pay the bill. It also comes with a 1 year warranty. Most of the time when I see these fail, it is because the operators are bulldozing pallets. This always tears up these drive units. They try to push 5 or more pallets causing hard stress on the motor and the drive unit. Usually the drive unit goes first.

I always use a matched set..I run a ink pattern to determine the correct setting for the ring& pinion. My Boss talked to crown. They have had a problem with breaking bolts.

Improper Shimming on the ring gear, or not installing a matched Ring and Pinion can lead to the Bolts breaking. We ran through this while back. Started installing mathced sets, and the problem went away