My Chamberlain/Sears unit failed when it was below zero weather.
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!