My convertible top isn't performing up to snuff:

The first function of the hydraulics is to raise the rear window. The second is to raise the rear decklid. Next, the rear window, as it normally performed, slowly lowers into the original down position, then the rest of the top recedes into the storage compartment and the rear decklid closes.

The misfunction is with the lowering of the rear window. Instead of slowly lowering into the original down position, it just abruptly falls into place. The job gets done, but it's not normal and is probably doing some damage.

I don't have a good understanding of the mechanics of the system. Can you tell me, where is the fault?

Thanks much to all. Dave