Fixing compression: new o-ring’s and Dow 55 or rubber conditioner.
The enemy: Teflon tape.
I’m sure you have heard of Teflon tape mods to fix cylinder head leaks on a V2 gearbox or air nozzle leaks on a bar 10 and all the random theories and “quick fixes” that you can do with a roll of Teflon tape on your Airsoft gun. The truth is Teflon tape dissolves in most lubricants, has a very low tensile strength, is designed for low pressure water applications, and easily goes everywhere in a working gearbox where it shouldn’t.
I have opened more gearboxes than I could count that looked like an Easter basket after their “mod” came off their cylinder head and wrapped its way around everything in a gearbox. Truth is, this method is more expensive then doing it right the first time. I’ve also seen hundreds of cases now where Teflon tape will partially dissolve and turn into a nasty gear-clogging goop inside your gearbox. At $30 an hour, I make a decent chunk of money fixing these so called “mods” for kids.
If your cylinder head leaks then replace the o-ring and lube with Dowe 55 or power steering pump leak stop. Instant 5 year fix. Teflon will do one or two games
before it fails. A basic o-ring cost’s $0.50 from most stores and saves you a lot of cleaning and headache.