My 1108 cap is so tight going on, I'm concerned about damaging the reservoir neck. I put a spacer/block between the bottom of the reservoir and the reservoir mount, so that I wasn't bending the reservoir downward when pressing the cap on. I also put a little clean brake fluid on the rubber seal and on the top of the reservoir neck, so the cap would rotate easier going on.
Maybe my 1108 cap leaked at the tubing/cap fitting because the clamp was not installed tightly enough. I'll crimp it a little more and see if that takes care of the leaking.