Dave's video is good and useful. I had problems with my Wessex Dolce, particularly the 2nd valve cap. What I do that works excellently for me is I put the valve in, press down on the top finger cap until it is sitting right on top of the valve cap I need to screw in. Just gently on top, and all while holding the instrument completely upright. I then turn the valve cap gently as if unscrewing it until I feel or hear a slight click. This tells me it is ready and positioned/aimed correctly for screwing in. Then I screw it in. This has been working every time for me. I used to take two minutes to get this cap on, even using methods like Dave describes. It just would not get in the right position to screw in.