Sears Craftsman 1/2-hp garage door opener problem

One of the door openers I inherited with the new garage has an odd intermittent problem, and I've not really found anything online that quite relates. I've gone through the adjustment procedure for both the upper/lower limits, as well as up/down force - however, that doesn't make any long-lasting effect.

When I initially set the lower limit, the door will travel all the way down, and provided I have the force set correctly, stay closed...at least once. However, with continued use the door will no longer close all the way - right now there's a 3" gap underneath. Also, despite following the adjustment procedure, the door will not lift all the way. It stops at about 5'-10" and refuses to go any higher, regardless of how much I turn the adjustment screw.

When we had the home inspected, this door was not opening at all. After talking to the seller about it, he said sometimes it goes up too far past the upper limit stop, and would get hung up. I've not yet had that happen. Although I did notice the chain was very slack, so I adjusted it before attempting any of the other adjustments.

I'm guessing there is an internal sensor that may be dirty and/or failing, but I've not been able to find anything about it online. Any ideas?

How does it determine the upper and lower limit.

Some of them use threaded nuts and limit switches on a shaft, some use limit switches tripped by the chain, and some use encoders that count motor revolutions.

If it's an encoder, then there is slippage between the encoder and chain, the encoder wheel has blocked holes, the encoder is failing, the drive chain is jumping, or maybe a control board failure.

Limit switches are pretty straight forward. The door should stop when the switch is tripped. Inconsistencies can be caused by bad switches or adjustments that aren't staying put. Switches not tripped by the chain can get out of adjustment if the chain jumps a cog or two.

In reply to Toyman01:

That's what I've not figured out yet. I didn't see anything obvious on the chain, so a cog-mounted encoder may be the method used. The chain isn't visibly or audibly jumping, and it seems to work fine otherwise, so my hunch is it's an electronic/sensor issue.

I've never disassembled an opener(only installed a couple) so I'm not sure if I can pull a cover, or otherwise disassemble it enough while it's still mounted to the ceiling, to see what method is used to determine the upper/lower limits, or watch it in action.

I've always bought these units - ten years is all I get. How old is it?

This website is awesome for all things garage door. You might find an answer there.

http://ddmgaragedoors.com/diy-instructions/

In reply to Datsun310Guy:

Not sure, we just bought the house. The garage was built around '97, but they look newer to me.

In reply to Woody:

Thanks Woody, at least PCB replacement is pretty easy. Though my hunch is it'll be more cost-effective to just replace the opener.

Just wanted to address one thing here. Have you operated the door released from the opener? Perhaps the door counter weight spring needs adjustment. The door could be encountering to much resistance as it opens or closes and that trips the opener to stop.

Sounds similar to my crappy Craftsman opener. It does the same even with the door disconnected.
Petegossett, consider a Sommer opener. No chain or belt. One moving part, the motor. And that's got a lifetime warranty

jimbbski & DrBoost, you both bring up excellent points. I'll release the door & check both its operation, and the opener's with no load.

I've had issues with the pin and the bracket the attaches the door to the chain/release pull bracket. If the bracket was all the way to one side of the pin it would bind just enough to act all weird. I centered it. Fixed it and add a bit of lube.

Same thing happened at my In-Laws. My FIL was messing with it for a while, and I centered the bracket on the pin, and BOOM, no more problems.

In reply to RossD:

Wow, how did you figure that one out???

I fixed one where the chain track support piece was anchored to a piece of wood that had been loosened when some idiot poorly installed a basketball backboard in basically the same spot on the other side of the wall. Since the board was loose, sometimes the track would twist and cause the chain to jam, making the door think it was shut or make it turn around and go the other way.

BTW, I was 15 or so when I fixed ours, standing up on a ladder working with no one else home. I didn't fully think about what might happen when I detached the track before I did it. Well, it swung away from the door, causing me to drop all my tools and fasteners on the floor and almost fall from the ladder. I was left standing on the ladder holding both the wall in one hand and the track in the other, but with no good way to re-attach, and nothing to set the track down on to retrieve the tools. One of those "Nice work idiot" moments that you really learn from.

I spent a bit more time with it this evening. The springs seemed really loose - like, when I lifted the door all the way open, the hooks on the ends of the springs were completely slack. So I hooked them in the next notch about 3" further down.

The opener moved freely without any load, so I adjusted the upper limit & it seemed pretty close. I reattached the door & started adjusting lower limit. It says 1-turn should equal 2" of travel, but an 1/8th turn made the door bottom out & reverse direction, compared to the 3" gap it had before.

I also noticed most of the cover screws were loose, so the PO apparently had been into it multiple times. Given the other electrical work I've found around the house, that's not a good sign. So I think it's about time for a replacement.

Look onto a Sommers. That's what I'm getting.

In reply to DrBoost:

Thanks, I'll check them out!

I was also thinking about the wall-mounted units...I think it was Liftmaster that Woody has been very happy with, but I'm not sure any of those would work with my doors? I believe they're all shaft-drive, but these doors don't have a shaft to attach to: