im still having the same problem people and its the fourth time.......my dad thinks that the plug holes are sratching everytime this happens......we've tried metal and copper, brace was the next thing suggested by pete but my dad wants to try plastic, what do u all think....is the block getting damaged or what!!!!!!!!!

 

Don't know if they even make plastic ones, but the plugs have to make a very tight seal, don't know if plastic is up to that.