[chaosnemesis]

imparting spin on the bb causes it to curve in that direction so hop-up on top, it'll curve upwards. Hop on top but slightly to the left will cause it to go up and left. The fact that your gun always goes left tells me that your hop-up is setup a bit off. Whether it's the bucking that has shifted. Worn rubber or your entire hop-up unit it "twisted" or barrel is twisted slight out of alignment.

Separate the barrel and hop-up unit and look down the tube with the hop on full. The rubber should come through the ported part of the barrel and see if the rubber is aligned with the bb feed chamber. If it's not aligned.your hop-up chamber is worn where it meets the inner barrel and you'll have to buy a new hop-up. If it's aligned then check the bucking. Even in the "off" position it's never really off otherwise Bb's will roll out of your barrel freely. Off is just minimum.

Sorry for the shit grammer. My iPod keeps auto correcting everything I type. Annoying as hell.