O-rings too big?

I received a Vertex v2 the other day with o-rings that were too big. The upper one was a straightforward swap for a slimmer one. The lower one was really fat and I had no suitable replacements.

I was thinking of wrapping floss or possibly using two o-rings. Maybe even sanding the original one down.
In the end I just pushed the outer sleeve onto the base and trimmed any bulging excess with a surgical blade. Took seconds and went from needing a rubber glove to remove the outer barrel to almost perfect tolerance to remove and replace.

Of course this will only work with o-rings you can get to.

 

sometimes you can soak orings in vinegar and they will swell. Depends on the specific composition from that certain manufacturer though.