[scottfab]

After it stick don't blip it.
Take the bellows off and reach in with a long screwdriver or stick
and push back on the big plates. If that does lowers it back then
your looking at linkage or the big plates sticking still.
If there's no change then look to the little plate in the middle below the
two big plates. It or the linkage to it could be it.
I have never seen any other source of problem to the symptom described.