This is similar to the problem I had, but looks like you've tried everything... In the end for me it was all about the belt rubbing.by korgon - General Mendel Topics
You should try printrun, i've been using it with my Ramps 1.2 and it does what I need, SD printing works great too From github: "This alternative approach is confirmed to work on Mac OS X 10.6.8."by korgon - RAMPS Electronics
Ok, so long story short, my problem was indeed due to friction of the belt and the large penny washers meant to keep the belt in line. There was so much rubbing that the penny washers had been worn on those sections. In order to fix the problem I used longer bolts and placed another 624 bearing under the first. I did this on all four of the x-axis belt guides and also on two of the y-axis beltby korgon - General Mendel Topics
I am using nophead's (http://www.thingiverse.com/thing:2079) pulleys now, they were printed on a commercial printer here at university and they fit perfectly on my motors and don't have any wobble whatsoever. I will try the extra bearings for the alternative x motor bracket think I have some 623s laying around somewhere. I will also add extra washers to try and remove any friction on the belt.by korgon - General Mendel Topics
I have been trying to fix this problem on my mendel. I've tried so many things... Still cannot seem to find the problem. I just replaced the pulleys with better quality ones, I have tightened, loosened, changed steps per mm, and printed one to many test parts. I also am using ultimachine belts, alternate x-axis and ramps 1.2 w/marlin. This is driving me crazy. Anyone have any insight into tby korgon - General Mendel Topics