No reason they shouldn't. I don't know just what goes bad in a WUR. There is a sort of filter screen (not a separate part, just a bunch of small drilled holesl) which can clog. Of course the bimetal spring might somehow fail, or the heating wires wrapping it go bad or have a break in continuity. There is a thin steel (stainless?) diaphragm in there. And a sort of barometric copper bellows piece. If the diaphragm goes bad, a water cutter or the like should be able to reproduce it. Crud can be cleaned out. This assumes it hasn't spent time under water or in an ocean. Rebuilders can adjust them so they give the proper control pressure values cold and hot.
What makes you think it is going bad?
