The diff is in good shape, the gears are solid, not worn, it spins very smoothly, no gaps or grinding. I have a feeling it is a combination of my heavy finger and the massive torque of the 1515. I wish I had a 1512 or medusa 60mm can to try.

The engineers at my job have some rubber putty stuff that we will fill it with tomorrow should the saran wrap idea to bind it not work.