Makerbot Extruders Uneven

[MakerB]

The left extruder hangs lower (or is positioned lower) than the right one, and when I print something, the left extruder scrapes across the already-printed material. how do i level them?

(i tried leveling the build plate, and i set it to be balanced correctly, i even used a bubble leveler.)

[Roberto]

howdy
First you should Level your build plate accordingly.
Then unscrew extruders from below, both of them.
Don't take it apart, just loose it.
Then stick thiny piece of paper or kapton tape on the left side (if this side is lover).
screw bolts back and see difference. If not high enough then use another sheet of paper.