Guys,
Finally saw the light and turned the seat base and raising/lowering mechanism over to Andy to dismantle and rebuild. Here's what it now looks like. I did get a NOS spring from LWD, the pile of rust is all that remains of the original spring. Decided to rebuild a conventional CMP seat since the correct seat seems to be "unobtanium". Should I ever find the real thing it would be an easy swap.
Peter