I installed and Excedy stage 1 clutch with a new OEM fork, TOB and machined the flywheel as per OEM specs. I never abused it and it worked fine until. The car was sitting for about six month because of CAS problem that I fixed (See my post In Engine..Section). The clutch is an Excedy Stage 1 with about 20k and it started slipping a bit at high RPM. The pressure plate feels very firm and the adjustment is as recommended by the shop manual. After driving it few hundred miles since it was stopped, it started shaking when engaging the clutch and slipping. It will finally hold but if I press the gas hard it will start slipping and shaking a bit. After about 300 miles since started, the shaking at engagement and the slippage got worst to the point I stopped driving. I am suspecting that a spring on the disc has broken and a small piece may be stuck between the disc and the pressure plate or flywheel. I like the feel of the pressure plate and I was wondering if it's OK to just change the disc if what I suspect is correct. Also, can anyone recommend a good replacement disc?