Hi everyone! So, after a successful coupling cap replacement (found here) with major help from larryderouin and dcgillespie, I’ve now found a new problem. One of my ElectroHarmonix Output tubs is arcing inside the tube. It looks like lightning because, well, it is. Anyway, I’m hoping it’s just a bad tube. The amp was previously serviced by AEA here in he Bay Area (they’re an advertiser in this site). I am mostly pleased with the work they did. Below is a list of the work they performed on this X202B: • Signal Capacitor Replacement • Inrush Current Limiter • Transformer Blowout Protection • Individual Output Tube Bias Mod • Regulated Power Supply Mod • Phono Preamp Mod • Power Supply Capacitor Replacement/Upgrade • 4 x matched new Electro Harmonix Output Tubes With the work listed above, what do you think I’m dealing with here? I’m hoping it’s just a bad tube. I’m worried it could be something else. Attached is a pic of the tube that’s arcing and a pic of the underside of the amp (taken before I replaced the bad coupling caps from the last lost). I must admit that this issue is certainly something that I may have caused. Carelessly, I had the RED speaker cable on the Left Channel hooked up to the “8” Ohm terminal instead of the “4” Ohm terminal. My speakers are 4 Ohm ADS L710s. I must have mistakenly hooked it up incorrectly after repairing the coupling caps. On my bench, the amp was hooked up to 8 Ohm speakers. So when I returned the amp upstairs I hooked it up fast and wrong. I’m a dummy. It’s true. However, I’m pretty sure that the arcing was happening before I replaced the coupling caps. Pretty sure… Help?