what is your chain slack ? is adjusted  with correct sag ? when jacked your chain should have near no slack.  i always set 1" 1/8-1/4 max with quad resting on ground with correct sag adjusted. 

Chain is going to be the same tension jack off the ground as sitting wheels on the ground . When weight is on quad is when you want no slack. I fixed a while back  carrier bearings was the issue, well the spacer was the problem. Putting to much pressure on the bearings making them drag causing the chain to jump.