Bear in mind that the RV-6 has a lot of metric bolts on the motor box. I don't know about the 10". I can check my 10" Dynascope drive box and DEC worm assembly for metric the next time I hit the barn. Some of the RV-6 (not very many) use a 4mm allen wrench for the set screws that hold the back plate to the RA housing.
Soak the allen set screws in penetrating oil. Clean out the socket hole where the allen wrench goes, even if damaged. You can grind the end off of an 'easy out' till it has maximum grab in the existing socket. Some people give horror stories on using easy outs. Some experience helps but a lot is gut feeling to stop before you break one off. In the case of an allen head screw, it wouldn't be as bad to chip out the remains of a broken custom sized easy out. Try to get a LEFT turn drill bit if you have to drill them out. A left hand bit might turn the screw out while drilling, it often happens.
Edited by apfever, 16 July 2023 - 09:41 AM.