I have an Allister ARD 11A garage door opener, about '88 or '89(?)
vintage that works sporadically. In fact, it doesn't work more than it
works. But basically, sometimes it works, sometimes it doesn't. It may
open, then not close, or it may work a few times, then not work, etc.

There is both a remote and a wall switch to activate the door. The
problem has nothing to do with the remote, as when the door does not
work, it won't work either way.

I spent awhile playing with it today, and found a few things out.

There are 3 relays on the unit, and when I manually activate them by
pushing on them, they work fine. I can push one, and the door goes up.
I push another the door goes down. The third is for the light. So,
the relays are fine.

When it does not work, the appropriate relay is not getting activated.

Maybe I'm on drugs, but it seems like it barely works in the summer
with hot, humid weather.

What can make the door work so sporadically?

Having the door work has become more important lately because I just
got a new convertible that is going to displace all the sports
equipment that is in the garage now. ;-)

Thanks.