I'm not sure if I'm allowed to mention other forums on here but here goes.
If you go to the Weirhauch Owners Club forum and look on PCP, there's a thread titled A&M Fill Port leak fix by XTXAIR's Darrin.
It's a video showing how to cure your problem.

Mod's, if I'm not allowed to reference other forums, please delete this and I will pm Woodpigeon.