I have a Craftsman 139.53990 3/4 HP garage door operator, with the 10' extension kit. It's worked well for the last couple of years, but a few weeks ago the sensitivity to the remotes degraded substantially, to the point where I had to walk up to the garage window with the remote to make it operate. All 3 remotes (which all have new batteries installed) plus my Homelink remote in one car behave the same way. I installed a remote antenna, which helps, but I still have to be parked in the driveway to open the door. Does anyone know if the receiver in these units (it's made by Chamberlain, I'm pretty sure) have any tunable components that might have to be tweaked over time? I've got enough knowledge and instruments to do that, but I'd just as soon not take the thing apart and find there's nothing to tweak. Sears would be happy to sell me a new receiver board, I'm sure, and I've written Chamberlain for advice, but no response yet.