[bobcowan]

Since it only happens when the rpm's are up, it sounds like too much crank case pressure. Simple vibration would also bring it up, but it would be more time dependant rather than rpm's

If that is the case, I would not try to secure the dipstick. That pressure has to go somewhere. Since the tube is the easiest route, that's where it will go. If you secure the tube, it will go somewhere else, like through a pan gasket, or RMS.

I would try and vent the crank case better.