XT M786 Shadow Plus Rear Derailleur

[Sock18]

I have a M786 derailleur, purchased the bike March 2015. In the last 5 weeks the lower jockey wheel has moved sideways on the bearing causing the chain to come off and jam between the wheel and the cage. Took it back to the dealer and they told me they fixed it, next ride it did the same thing, this time resulting in some blood loss...

So, back to the dealer...This time they replaced the pair of wheels.

Next ride, after the first 20km's the new wheel did the same thing!!

Anyone else have this issue? or know what could be causing it??

[Duck!]

Have you checked the hanger and/or derailleur are still straight?