the ksc 18c is one of the most problematic full auto pistols on the market. the internal design of the pistol has a lot of moving parts that tends to wear out quickly. most of the glocks that i fixed are ksc 18c's. one of the first things that go, apart from the ones parts mentioned above, is the fire selector mechanism and the hammer and striker assembly. all those parts are high stress parts and tends to wear. unless you're comfy tinkering around with stuff, look for something more reliable. there are scores of potential problems customers have run into in diffrent forums. read a couple of them.
for 60 bucks, i'd bet that that pistol is close to failing. or is not what the owner claims it to be. if you decide to buy it, be mindful that that particular meeds a lot of looking after.
"May you fight with the strength of ten full grown men."