Will not overlook to re-seal the gearbox with RTV after you have discovered the correct blend. Even even though they’re referred to as “gaskets”, they will not likely seal your gearbox on their possess.
If every thing looks regular, attempt 
modifying the equipment-mesh. This is accomplished with the mylar “gaskets” that sit in between the primary gearbox situation and the enter/output caps. Try introducing or eliminating some of these spacers until finally your gears have roughly 1/eight”-one/four” of totally free play. Professionals can order replacements ($1-two) in varying thicknesses, but we recommend the rapid and dirty method of reducing your own out of a sheet of mylar.
“Groaning”, “creaking”, or “popping” all seem variety-of equivalent above-the-telephone. The best point to do is to disassemble your gearbox and just take a look at the gears and bearings. The concern will usually current itself in
the way of broken/lacking equipment tooth, toasted gears (like that photograph on our residence webpage), or blown bearings.
My Gearbox is Groaning/Creaking: