I have an old but lightly used ultrasonic cleaning tank where the solder joint between the leads (wires) and ultrasonic transducer surface has failed. I can (and have) soldered them back on, but they stay on about 5 minutes and pop off again. I strongly suspect it takes a special solder because the transducer surface (there are two leads on each of 2 transducers on bottom side of the tank) is not metal; possibly ceramic?? In any case, a soldering iron doesn't burn it, but ordinary solder won't stick. Leco and Branson seem unwilling to help (surprise!!). Anyone know what will work?