ORIGINAL: mtracy
It's not an issue with rough collective usage. The heli will be in a stable hover, then it will start to bob (looks like an exited dolphin nodding yes!). Only lasts for 1 - 2 seconds, then settles down, with no action by me.
The sticky collective isn't necessarily limited to the grips. Put a little light oil on your shaft. Your swash might be getting slightly hung up. and see how tight the links are. They should be loose but not pop off on their own.