There is a bit of hard and brittle black plastic like substance that has leaked from my gyrocompass gimbal (likely varnish from the gimbal motor) into the gimbal bearing.

The gimbal's rotation is not as smooth as before, and sometimes take a long time to settle to true north and has slow rate of turn alarm.

I tried cleaning the bearing with contact cleaner solution but this doesnt really work. I cant use WD40 because the bearing is actually part of a slip ring with carbon brush; WD40 will form a film and hinders the electrical contact on the carbon brush.

The manufacturer refused to help on this and replacing the whole gimbal as suggested by manufacturer is very expensive. The gyrocompass is actually TSS Meridian.

Do you guys have any ideas how to clean up the bearing? Thanks.