Over the past several months the operation of my CV top has deteriorated. At first, the top would go up partially then stop with a "Soft Top Failure" code. I could then re-start the motion to completion. Now the top will not go down at all. I can hear the pump start and run for a second and then stop with a "Soft Top Failure" code. My local shop claims that the pump impeller has failed. They have offered to rebuild it with a SAAB rebuild kit (with a metal impeller versus the original plastic one) for a total bill of about $600. Does this sound kosher?