LMichaels
TVWBB 2-Star Olympian
Patience Grasshopper (only us old farts will understand this). Anyway penetrating oil and patience don't try to unscrew them all at once. You may need to only take them 1/2 turn or less, than turn them in, a little more pen oil than another 1/2 turn and so on. Eventually they DO come out. Whatever you do DO NOT USE A HAMMER AND PUNCH! After all the years of heating/cooling cycles the aluminum casting will be VERY brittle and it will shatter like glass