But if the service is done on a regular schedule this isn't a problem either.

 

Galling on the Stainless I agree, But you would have to be aware of the galvanic corrosion on that the aluminum derby cover.

 

Galling occurs while the fastener is turning.

https://www.grainger.com/content/sup...galling-basics

 

Petroleum jelly on a q-tip to kill the rust in the thread bore and the fasteners; gotta kill the rust. Run a thread restorer (not a tap) thru the bore and use a little blue Loctite. In my experience rusty derby fasteners are rare; never happened on any Harley I have owned. I changed all the fasteners on the last two I owned to 12pt ARP SS fasteners.

 

actually, you can use common johnston paste wax. when it dries with engine heat, it acts as a mild thread locker, perfect for case fasteners.
if the hole is not buggered, do not run a thread tool, just takes away precious metal.

 

A thread "chaser" does not remove any material; just cleans and reforms threads. Petroleum jelly will dissolve the rust and the thread chase will clean the threads.