In looking at the base of these seats, it became clear I was sitting precisely on top of the hump in the base designed to prevent you from slipping rearward. Also the seat was too wide to allow my legs to drop down at rest.
I decided to customize my seat. I removed the plastic hump from the base with a Dremel tool. I covered the hole with a piece of flat plastic. I filled the hump void with foam and trimmed (somewhat softer allowing me to "settle in" nicely).I fabricated a new hump in aluminum and mounted just above the seat latch. I made a new void in the foam for the the aluminum hump. I used a sander to narrow the foam part of the seat so my legs could drop down. I made a pattern for the narrowed top and sent it to Suzy at Cheeky seats to make and new cover. It fit nicely though I chose to staple it on to get a tight fit.
I love my customized seat. Fits perfectly. Shout out to Cheeky Seats for great customer service and work.
If you are looking for a solo seat (new) or gray Primavera seat cover (like new) ;-( Check the classifieds.