I have a flipper that sticks up occasionally for mechanical reasons. A little touch gets it back to operational and sometimes just hitting the flipper button again does it. I understand that something is binding up and I have read a dozen things I shouldn't do (WD-40, graphite, etc) but precious little about what I should do. The spring on the solenoid seems strong (stronger than the other flipper for sure). I used compressed air to clean it out which worked pretty well for a while - seems like it spread a little bit of natural graphite all over. I can't get the flipper to stick by manipulating the flipper and other parts of the assembly, trying to bind it up. The travel seems to be appropriate and it never touches the playfield.
What has me concerned is that it has a little squeak/grind when I manipulate the flipper, like metal to metal contact. Should I take it out and polish/clean the metal parts or is something worn out? The squeak doesn't seem to come from the solenoid part of the flipper but I can't tell exactly where it is coming from in the rest of the assembly. If I do polish parts, I assume I can use some sort of polishing media that I would clean off after. There is a little bit of corrosion in my machine; it has probably dwelled in a basement for most of its 30+ years.