I agree, the problem with the old hose was that it let too much air through. If your new hose is not as wide, it may solve the problem. I don't have a copper cap in my SVT, I have several washers (I guess they are nickel) and they work fine (just make sure they can't get sucked in). Checked them out over the weekend actually and they have some slight discoloration, but no melting or anything like that.
