permatex gasket remover works great. spray it on let it sit for5-10
minutes and wash off. repeat until your powervalve parts look like chrome. oh yeah wear gloves and a face mask or respirator. i got a good wiff of that stuff when i used it, it was just before my bedtime
and i was all fubar from it, and i really though i might not wake up the next morning, but i'm still kickin!!!