Soooooo…
I know that this is a VERY late response to this, but I believe what you were experiencing was static buildup from the dolly.
We experienced this a few years ago when shooting on the Canon XL1s on a Fischer 11 dolly with standard square wheels and steel track. For some reason, we kept getting hits on the video, but not when it wasn’t on the dolly.
We solved the problem by plugging in the dolly and leaving the “pump recharge” switch in the OFF position. What this did was ground the dolly using the same ground as was being used on the monitor. (Both were plugged into the same socket, but in hindsight I don’t think that was necessary.)
We got the shot with no further problems, and the issue with static build-up went away after we left that studio location. I’ve never experienced anything like it since, but that was our solution and it worked (although we lost about 2 hours trying to figure it out. Ugh!).
Cheers,
Jim