Hi. I have an amateur radio repeater from the 1980's that I am cleaning up and the board has some crusty brown stuff on it. I thought maybe some caps had leaked but realized it doesn't have caps that would leak like that. In your opinion, would it be harmful to use spray contact cleaner to remove it? I am getting it ready to replace the pa module and the driver mosfet. Thanks in advance and I am learning so much watching your awesome videos.