garage door opener stops

My 14-year-old Sears 1/2 hp single door garage door opener has suddenly begun stopping half way up. After excersizing the up limit screw a bit it will go all the way ONCE then it returns to the half way situation. Coincidentally the weather here in New England got really cold this week.
What going on?

 

when youre opener stops does the motor continue to spin? I would open the cover and see if you have alot of fine white shavings in the bottum. while you have itopen try operating it once and watch what the limit thumb screws on the left do. there is a thin contact at the top and the bottum that the small plastic wheels make conctact with when in the proper position(either open or closed). Youre problem is kind of hard to trouble shootaas there might be other signs that you dont notice in the operator head. If you cant find anything ther please post back if you notice anything else. One note however after fiftenn years you more than got youre money out of the old lady it might be time to put her out to pasture. If you watch youre sears sales you can pick up a new one with two remotes and a keyless entry for around 130.00. most repair parts will run you from a third of that and up. hope some of this helps.

 

Time to replace you opener. Your siccuit board is going out for one thing, and probably nylon gears also. Openers are only made for about 7 years. You have one of the older ones, so it was built better. No days Genie's are built in Mexico. I personally an anti Genie man. Lots of problems with them