“Everyone behaves badly--given the chance.”
― Ernest Hemingway
Like many of us found out during our younger days with a pretty girl on the beach. Sand can find it's way in anywhere, even with a towel.
The one item any would be reel repairman really must have ( before you ever start tearing down a reel...) is the schematic for that model. Without it you’re just guessing.
Mineral spirits (in the store it’s usually labeled “paint thinner”). I drop each part into a small bath of the stuff, scrub gently with an old toothbrush- then allow to dry on a paper towel. This removes all old grease and oil leaving the metal or plastic part in-harmed. Once you’be done that you can plainly see if the part is good or needs to be replaced. I was taught how to clean and repair reels at the first tackle shop I worked at back in 1972....