Do you run in dusty and/or wet conditions?

Sounds like the bearings need to be cleaned and lubed. Gears don't normally squeak. The gears might break and you get a crunchy sound, but not squeaking.

Open up the gear case, paying close attention to where everything goes, clean everything up with some plastic safe electronics cleaning spray, and re-assemble with some white lithium grease on the gears and bearings [a little goes a long way].

As long as the bearings can be cleaned and freed up, it should quiet down for you.