yes you can adjust pressure but it will burn up the motor. If you got 10 years out of a sears motor you can be pleased. I don't install them because I don't trust their longevity. If you decide its time for a new motor, I strongly recomend LiftMaster. This is my job and I only install LiftMaster...
http://www.liftmaster.com/consumerweb/pages/productmodeldetail.aspx?modelId=1443
I have installed these and I love them. If someone were to buy a door from me and they had the clearance, this is what I would try to sell them.
I would suggest trying to return the genie, if not an option keep...
Where are you located?
I noticed you mentioned grease. Have you greased the track or rail? Do not do this I repeat do not use grease on your track where the rollers are.
How old is it? Could be a number of things.
7' high is the industry standard for garage doors, but personally I like an 8' high. Most likely you will never run into an issue with 7' but hey bigger the better right?