Don or someone equally well versed in garage door openers, this one's for you! I've read some of your other entries, and tried some of your other suggestions, so we know you are wise!

We have a Liftmaster .5 hp. We aren't sure how old it is; we just moved in, but the house was built in 1988. The problem is this:

When we press the button, we can hear the hum of the motor, and we can see the track moving, but the "trolley" pieces do not stay together and, hence, the door does not move.

In other words, the "trolley" seems to be a metal piece made of two parts--one attached to the chain, the other at the end of an elbowed piece of metal attached to the door itself. The two parts are connected, it seems, by a pin on the elbow that goes into a slot on the chain and a spring that fits into small holes on each part. The two pieces no longer stay attached during the cycle, and we cannot see where another connecting piece might go. WHen we manually attach them, the door will move for about a foot until the pieces separate again.

Any idea if this is something that calls for a new opener, a repair call, or a reasonable DIY job? We are VERY green, I must add.

Thanks for any and all help,

Rich