Ed, this has been discussed several times and fellas have come up with various solutions. Most of these require that the spring circ-clip be tossed. Some like to use a worm gear clamp to hold the cap.

I tend to go the simple route. I remove the circ- clip and add a piece of silicone rubber tubing onto the cap to hold the cap in place of the clip. Removes easily but holds firm.

I don't use the extra spring that's included for contact.. In my experience it isn't required.