Had similar problem with my 2 rear ones. Called HWH and explained what the service person told me and was told service was flat out wrong. He walked me through a couple trouble shooting steps and confirmed they were shot. They were less than 18 months old.
First thing he had me do is loosen the lower bolts and try to raise them. They performed a lot better. Don't recall if they were normal retraction at that time, but much better. Actually, now that I think of it, that was the only thing we did.
Mine have bolts at the top where they attach to the frame. There is also lower bolts attached to a bar that only attaches to the opposite jack, presumable for lateral stabilization. I loosened these.