The contractor put a B750 belt drive opener in during remodel. Very slow my old lift master was a lot faster and quieter. A plastic cover was busted by the contractor before installed. Contacted Chamberlain support through their web site to see about a replacement cover. Tech support replies then act like they do not receive my reply to them. Waited a couple of weeks and try again to have the same thing happen with a different support person. Then Chamberlain sends me a survey about my experience with support. My responses to the survey explained what happened. I am still waiting for a reply to my survey. I mentioned if no reply that was their reply.