I must be lucky in that all 4 of mine are still working, but the passenger rear is a bit squidgy when pressed. I do however have intermittent issues with the touch sensors based on the weather.

My driver's rear is the only one that works - not the end of the world but now I've figured out which works and don't I have an urge to fix.

Is there not a case to be made for fixing the existing units replacing the switch or whatever vs having to replace the entire handle unit?

Without having one in front of me I don't know how sealed or 'serviceable' for want of a better word they are.