When I bought my used Merckx 8 years ago I had a problem with the left shifter body which is made of carbon. I can't remember what was wrong but I only needed a new body, not the works inside, so I bought a Campy Record brake lever body (for people who use bar end shifters) and converted it, saving a €100.
Then today I was cleaning and lubing my Viner Maxima, which has never been the same since visiting the muddy strade bianche near the beach at Brussa last month. Hosing it down and oiling everything didn't help much so today I tried re-doing it all. The front derailleur was still punchy so I tried cycling it a few times and the carbon fiber lever snapped off. I'm a pretty skinny guy but apparently I'm powerful enough to snap carbon parts with ease. So I went to the now semi-retired Merckx and cross-canned the left ergo shifter, again. Hopefully no purists are offended by my mix-and-match gruppo.