Grant:
Yep, I do hope that is the problem. It always did just fine at lower throttle settings, but would get sickly as I increased throttle.
The Cozy will be attached to the Triumph for sure.
The current plan is the C5 will get a good touch-up and cleaning so I can sell it to make more room in the garage. I'm seriously running out of space, and decided I've too much time, $$$, and emotion invested in the Electra to let it go anywhere soon. At least for now. I've been known to change my mind.
And it's a foregone conclusion I won't be able to get anywhere near a good price for it.
Gizzo:
The stuff may have eventually broken away and the problem may have solved itself, but once it expanded it was almost as hard as concrete. Surprisingly so. Hard enough to seriously increase the back pressure at higher throttle settings, anyway. I do think this was the issue all along, but I'll only know for sure once I get it back together. Valves and rings are in excellent condition. That was my big concern, so it appears all the stuff I ordered except for the seals will become stock for future repair.