My Chamberlain/Sears unit failed when it was below zero weather. (sheared helical) It is 15+ yrs old and had been making noise for a long time. So it shouldn't have been unexpected...just very inconvenient. I checked online with Sears and 1stdooropeners.com. Both were OEM so I went with 1st ($6 less) Parts came it 2 days...about a 2 hr job in 10 degree weather. Funny how you miss the convenience!
p_z