About 15 years ago my brother gave me his Vox Pathfinder 15 amp (pre reverb). It was awful, couldn't play chords at all without extreme breakup. Had to turn gain way down and play one note at a time to use it at all. Also the tremolo didn't work and the input jack was shorted out. Fast forward to late 2020- I'm looking at small vox amps when I think, maybe I should try fixing the Pathfinder first? Replaced input jack with a spare one from a guitar, but it still sounded awful. Searched the internet and found on TDPRI info about a malady called "Cambridgitis" due to bad opto-couplers. The source quoted in the prior thread no longer had the part Found this part #VTL5C3 for about $10 shipped on eBay Installed it and now I have a good amp. It sounds great to me. Thanks to those who have shared this solution in the past.