During re-assembly the Clip got out of place and damaged its groove in the cap (very soft aluminum). When the cap would not tighten down evenly and smoothly, I removed it and found the damage. The question is can any used cap from a 426 engine work or is it a machined set to the head? Yamaha does not sell the cap separately; you have to buy the entire head/cam assembly. Appreciate the advice and if you have a source for a used cap (assuming interchangeability), I'd appreciate that also. Regards.