This is a Stanley garage door opener chain drive style, 0.5 horsepower.
Model UT300 made in 1994.

The problem is when I try to open it, either from the remote or wall
unit, it travels open for 1-2 feet and stops, and start ticking (with
Di-Da-Di-Da sound in one second interval). This is the same with or
without the door engaged.

I have tried the opener without the door engaged or the chain engaged.
in both cases got the same results, so the problem is neither the door
or the chain or the rail...

I guess the opener is actually fine but there are some procedures to
follow when setting up. I don't have the instrution manual as the
opener is from previous owner of the house. Could someone kindly
point me to the right setup proceudre or maybe email me the right step
or the related page?