One (rig) i have done from time to time on allen head screws is to get the famous bumper chrome paint :loony: and use a small brush to dab paint inside the screw head. Also helps to prevent rust.
you ain't gonna like this probably, but you can get those chrome buttons from your local harley shop and put a dab of high temp silicone on it and plug them in. it will pop off with a knife blade and keeps them from rusting.
I believe it is the metal from the allen wrench impregnating the socket head cap screws to make them rust. Get some stainless allen wrenches or spray then down with wd40 before using them. I changed my allen heads to stainless a long time ago.
Groovy