Since its an intermittent thing, though, i'm thinking some 'event' is triggering it. So I would suppose i wouldn't see anything with that test. I may try it just to be sure though. I figure it can't be shutter related though since its ever 8 frames... i.e. not every 2.
I'm going to try to shoot something severely undercranked, and see if the timing of the mishap changes. If it doesn't, then I know its definitely a mechanical function. If not, I'm not sure what that tells me =(.
I'll keep you guys posted.