Thanks everyone for the tips.
My first step will be to sand off the front edge of my foam seat--(Bill & Robert) Yep! there is pressure on the back of my thighs--right at the front of the seat.
More foot ball and heel support,or Full foot pads (Lee) and the article Jay referenced is full of good information.

I think somewhere during my 4 years of paddling my butt got boney-er, I connect and press with my legs more consistently (if I don't press with my legs and feet--instant loss of 1/2 knots) and I began patching the problem with inflatable pads and pieces of foam instead of really addressing it.

Thanks.
Will