garage door opener

I'd open it up and look at the travel adjustment. If it's like mine it has plastic screws that moves where little switches are tripped. Switch probably isn't closing. I can adjust mine to stop inches before the bottom, which I do sometimes to leave a cat opening. These old ones do not have the safety beams so they use excess force to reverse. If it thinks it has not reached the bottom because the bottom limit switch is bad it will reverse when it can't go down any more.

That sounds right, is it easy to replace the switch, turning both directions doesnt seems to make any difference.

You are right the stop switch is broke, the plastic holding the metal bar broke, What to do. I could glue it, what glue would hold?

Use small machine screw or contact any garage door opener firm with make and model and see if they will sell you the part.

I'd try superglue or pvc pipe glue. But I agree with your concern, plastic is hard to successfully glue. Can you replace it with a metal bracket? Or like Bob suggests, drill a small hole through it and use a tiny bolt or screw.

I've had some success finding obsolete parts on ebay. You could also watch craigs list for a used one cheap as a parts source.

If I could wrap it with shrink wrap tape after using your idea of PVC glue it might work, I have it working now fine and held on with alligator clamps, yes a scew is an idea but not much plastic there or room to work on it, thats the hard part, the area of work

You'll probably need to remove it to make a really good fix.

would a big blob of JBWeld epoxy hold it together?

earlier than 93 model year.

I think it's different it has 3 long plastisol screws

Maybe but now I have 2 alligator clips holding it ok, maybe epoxy and clips

Whatever works - Now that you know the problem, if it happens again when the epoxy and alligator clips fail you will know what to do. Only concern is if the clips and epoxy fail, will they damage anything else in the mechanism.

e:

No it's at the bottom of the unit , it just falls on the case, I saw them on eBay for 12$ so I will get one