Mike.......oil pressure gauge is connected to same "T"-block at rear of flathead engine that the oil filter is connected to. So yer filter could be completely clogged and you will still read oil pressure. Its the LAW. Hydro-dynamics law.
As a rule, the oil pressure gauge is semi-bulletproof. Howsomevers, as with all things mechanical, it could come apart inside. New oil pressure gauge, $15 (cheap) ........Dell