The only problem we had with our used 2619 was the tailight/stoplight sockets. The lights gave us problems almost immediately. The previous owner stored the TM outdoors in a humid climate, which no doubt contributed to corrosion of the light sockets. A little sandpaper on the contact points remedied this problem. We have stored the TM in the garage since, and have not had a problem with lights since. If you can do it, keeping the TM out of the weather is "good thing" (as Martha S would have said)
Also replaced the vinyl and carpeting with laminate flooring but that was a modification of my choice, rather than a problem with the TM. We've been pretty lucky so far, but I think I'll get two new tires before my luck wears thin!