The garage door guy arrived at about 4:00 PM again today - it seems he works on our house for about 90 minutes at the end of each day on his way home. Today he installed the motors, and says that he'll finish up tomorrow by connecting the wires and installing weatherstripping. We specified belt-drive openers because they're super-quiet, but he says there's another benefit: the standard screw-drive mechanisms lock up in winter when the grease on the screw gets cold and becomes so viscous that it stalls the motor!