I swear every thrift store find I grab with a loose jack has been hacked up by someone with a $15 iron. Last week I got a pair of Sennheiser HD 280s from a guy on Craigslist for $20 and the left channel was dead cause he bridged the ground to the ring. I spent an hour with my multimeter tracing his mess and had to redo all 3 joints. Come on folks, learn the TRRS pinout before you touch vintage gear. It's not that hard to look up a diagram on your phone while you work. Anyone else run into this with old headphones or am I the only one who checks continuity first?