Hhm, seemingly we are coming from different experiences. How many used modules did you buy and how many were broken? I actually bought a new Doepfer module from a well known and respected dealer. A few days after when I unpacked it I found a popped capacitor and burn marks on the PCB. When I returned for a replacement they assumed I had destroyed it myself and denied me compensation. This happened to me 3 month into going modular. This may be a rare case, in my experience as rare as module seller intending to cheat you.