1957 Tri-Pacer, certificated. It has a manifold pressure guage, looks like it came with the airplane. I have no idea why. It's alive, so maybe I ought to learn it against the day I get a complex aircraft. For the present, though, it looks like some bug cocoons have gathered in the bottom of it. Can I legally unscrew the panel cover, attempt to remove the face of the m.p. guage, and clean it out? It really BUGS (sorry!) me. Thanks.