The short life of things used to bug me but we live in a throw away world and boilers are part of that, it is needed to keep the ever increasing population employed doing something
It has been hard to stop carrying so many bits and pieces for boilers, as now even alot of parts you can not repair as sealed units or so flimsy to work on
Its an age thing, the younger plumbers think nothing of taking out and replacing and I am getting like that now, after a certain make of boiler gets past a certain age, I just advise replacement and I find more and more of the sheeple except it as they are used to the situation with other equipment around them
You also have to be careful repairing older boilers as can effect your reputation, as you repair one thing, another goes wrong the next month and the finger gets pointed at you rather than the aging parts in the boiler, same applies in other plumbing equipment
imho