This is an old Delta (at least 20 yrs old) I'm afraid I'm going to wring the pipes off. I've tried tapping around the dome cap with a tack hammer to help loosen it up. Also poured vinegar over it. Any suggestions?? When I try to unscrew it with channel-locks the whole assembly tries to turn, it feels like the pipes are bending. I'm afraid to try heat for fear of melting the guts. Any suggestions would be greatly appreciated. Thanks in advance, Craig