Came across this very good video showing what's in the guts of the typical RF-45 mill & one of (many apparently) potential sources of gearbox noise. Mine was a growler from day one & seemed to be getting worse over time, but I lacked the confidence or know how to tear down, investigate & potentially source parts. Who, knows, it may have been something relatively simple. I wish there were other videos like this at the time. The closest ones was CNC conversions & they basically turfed most of the gearbox mechanism anyways.