I have a overhead door model 45A it opens the door fine, but slides back about a foot after its opened. When trying to close the motor hums but won't engage to close. Any hints on adjusting it to correct problem? Thanks

Is the trolly all the way engaged? And try with trolly disengaged.
When it slips back a foot, does chain move with it?

Do you have a remote for yours that has dip switches? I have one and can't find the switch codes for my replacement remote. Would you happen to know the code?

KJAMBUG. Make the DIP switch on the receiver match the transmitter. Should work if the frequencies are the same.