These days, whenever an older bike comes in we routinely check for earwax and perform preventive or corrective procedures. We hardly ever replace a shifter anymore.
The road shifters are somewhat less prone to earwax and much harder to service if they develop it.
Campagnolo's Ergopower road brifters do not develop earwax. That's the good news. If something goes wrong you can repair the shifters using Campy's detailed diagrams and fully-listed spare parts. The bad news is that you have no excuse not to.
The fun starts here
Follow these simple instructions
It doesn't always have to be like this
This is on my mind because I just did ratchet springs in a Campy lever last week and now I'm doing about the tenth de-earwaxing of the young season on a 1993 or '94 mountain bike with Shimano trigger shifters.
No one has brought me any of Campy's flat-bar shifters, so I don't know what they're like inside. If you only learn things as you need to you have plenty of brain space left over to use as a playroom.