Mine, too, has the same problem; everything's just sloppy and moveable. I think it's just inherent to the design/build quality and something that you largely have to put up with. It certainly doesn't seem to have the best tolerances around. For example (and I'm saying this without taking mine apart, so take it with a grain of salt), mine seems to be moving in a way that suggests the barrel has too small a diameter and/or holes for pins or bolts that are too small.
This seems to correlate with an I26 displaying similar problems that I relubed recently: on that, the mount itself screws in tight, but the lens wobbles on the mount. This is because the mount is a separate plate which is held in place by the screws which fix the back plate to the focusing ring, sandwiching the mount in place. The problem I noticed was that the unthreaded holes on the mount's plate were slightly too large, allowing the movement and wobble I was experiencing. It wouldn't surprise me if the I61 was a similar construction with similar issues, and I can't imagine any way of fixing that without machining a new mounting plate OR making new (and more precise) holes.
