UPDATE to Blown breech o-ring on Bobcat M2...

Dear All,
Hope all here are well! Just to drop a line that the o-rings suggested by Tony T's post (also travels4fun) arrived . These 0-rings 009 Silicone seem to work well (McMaster-Carr so far. The Bobcat's probe does not seem to know the difference. Will see how long it lasts and carry spares on my outings. Installing took 30 minutes. Used only a hex key and fingers....
Now turning my attention to my Hill Pump MK3 and the little green o-ring - my first rebuilt of the four Hills I own.
Thanks again to all in their posts and this forum!
OldFalc