Joe, its not uncommon to hear the piston leaking down especially in those engines. You stated that they have compression, but did you try them with fuel in them. Any carbon that was on the cylinder walls and piston should be left on due to the inferior fits and quality of metal they were made of. I own several of the .19's which all but one vitrually wore themselves out. I had one engine run exactly one time before it was worn out. I own 6 of the .35's which I've had much better experience with. The lightning bolt cases had a bronze crank bushing while the other shiny cases didn't. The bronze version provides a better bearing surface. I just really haven't owned one of these engines to the point of wearing out a case due to the piston sleeve fit wearing out first. Its imperative to use high castor % fuel while running these engines. The needle valve assmby's can still be obtained through MECOA corp. I've even substituted a Fox .35 needle valve in them which works. I'm a fan of these engines and learned to fly with them so I make a valiant effort to baby the ones that still work. They do have a great sound and a very nice run to them. Ken