mrjohs wrote:
Ok, so I have tried with a few different o-rings. If I do the one from the spares bag which is about 14mm OD, there is no way I can force the bell down over it
Well, I dug my calipers out, and yes, that 14mm o-ring is the correct one. As you know, it's quite a stretch to get it onto that shallow groove, so ends up being a fair bit less than 1mm in width.
I've tried using the 14mm o-ring in my spares bag too, and I'm just not having the same issue you're having.
I'm a bit stumped now. By rights, that o-ring should work fine. :-(
It's twelve inches long, but don't use it as a rule...