Y Axis Moving Unevenly / Wobbling

My Y Axis isn’t moving evenly. The left side moves very smoothly. The right side however takes a second longer to start moving and as a result the spindle wobbles. I already adjusted the belts some, which helped a bit, double checked the makerslides were all screwed in securely, and adjusted the eccentric nuts so the wheels were looser and tighter to no avail. Is this an uneven motor power problem? Is something assembled wrong? Does anyone have any idea how to fix this? Hopefully you can see in the video the wobbling I’m talking about.

Movie on 1-10-16 at 1.10 AM.mov (8.7 MB)

from what I just saw it looks as if the belts are to lose , I use a fish scale and a ruler to check and make each belt the, don’t hold me to it I think I was 3.0 lbs. per 1" lift in the belt. I also found that I let it thru some test job to get the belts straight out and did readjustment I also found that you need to lock each end of the belts using a wire tie… I made all adjustments with “X” axis in the middle of the “Y” axis

But I checked all the wiring… is there anyway to specifically test that motor?