Brilliant! Solved my problem on my 3330.
BTW, if you're squeamish about pulling on the belt to move the scanner assembly, there's another way. Every time you plug in the printer it will move the assembly about a half to 3/4 of an inch towards the small glass section. Just keep plugging/unplugging and it will eventually move all the way over. You can tell it's there when it makes a bit of a "clatter" sound when it's supposed to be moving (different from the sound it's been making every other time!).