Would vasoline work? I mean it is a good lube ;-) I'm going to lap my piston again tomorrow at work. In the same way I would do a valve to seat on a cylinder head. Would starting with a cordless drill slowly to rough the seat be too harsh? Then finish it by hand, I know forge do a service kit but once I've lapped the piston in would a new piston never fit? Or just not needed? Does anybody have a spare shim? Or do I need to swap to yellow spring too? Is the spring you need linked in any way to how/ who mapped the car?