This garage door problem really has me stumped.

Fortunately here in Southern California it doesn't rain too often (except
for this year).

But when it does my garage door halts about half way down and then retracts
(i.e. opens).

I know this can be a symptom of a door sensor problem. But I just moved in
and the infrared sensors, which are usually on either side of the door near
the floor of the garage, cannot be located.

It is a Sears 3/4 HP Garage Door Opener (chain drive). Similar to the GDO at
http://www6.sears.ca/webapp/wcs/stor...ctId=158060864

But a bit older, although the GDO technician that came out several months
ago said he did not think it was too old (whatever that means). By the way
he was also surprised that we could not find the sensors in their 'usual'
place.

I lubricated all of the recommended places and even increased the
screwdriver adjustment for the door closing speed/pressure. Still no joy.

Any ideas?

As always, thank you for your time.

Michael