The collective should not pop up when the friction is released. It should be set up so that the spring capsule is 'over centre'. The manual tells you where to measure and how much. At rest, the lever should stay where you put it for approx the first inch or so of travel and then spring up with force. At normal RPM it should stay where you put it with no friction. If not it's adjusted wrong. If it wanders up there is too much spring pressure and the capsule should be unscewed. Make sure you are turning it the right way. From your descripion I think you might have increased the pressure if no threads are showing. Make sure it doesnt come apart. That would be really bad.
Ive just got bdkd back in the air and had a similar problem on the first flight. The anwser is you need 'more over centre' ie. the collective moves more before the spring kicks in. This makes a heck of a difference and the balance between over centre adjustment and spring strength is a fine balance.
Agreed. It's horrible with too much up pressure.