I’ve 38x42 O rings are you sure they are not that size?
It honestly wouldn't surprise me if there were different size pipe, flanges or seals used somewhere along the way, but (based on the crude tools available) a 38x42 wouldn't
theoretically fit in the recess of the pipe I've got. Maybe - like a few things - with a bit of lube it'd slide right in, not sure
Rather than pontificate about what it could be, or take a guess, wait for the post, find it's wrong, take another guess, wait for the post again, then resort to Nick's magic o-ring rope - I'm instead going to pop down the road some time this week to
Simply Bearings, pipe in hand, and have their experts scope it out. If push comes to shove, I'll walk away with a best guess and a fallback - with a high degree of probability that one or t'other will
just work when I come to refit it at the weekend.