I own a Trek 1.2 with a triple chainset, and the front shifter has recently been giving me nightmares.
Unless I set tension to the absolute minimum from the barrel adjuster, it won't shift down at all. When on the middle ring, the derailleur is rubbing the chain towards the bike, and the limit screws don't seem to make any difference.
And, starting yesterday, the lever won't come back into position when shifting up, meaning that I have to push it by hand. Also, moving it requires a lot of force compared to the rear shifter, with witch I have never had any problems.
So, I was looking for some advice related to adjustment. It is steadily getting worse and worse. I would like to fix it myself and avoid going to the local bike shop - the prices in Central London are way beyond my student budget.