Is the Wired Remote for the Cambridge Soundworks SW320 Speaker System able to be opened and repaired (the varistor replaced) ? OR - is there a product "out there" that can replace the entire Wired Remote unit ? The problem is - that the varistor is either worn or very dirty. Unless I can position the wheel in EXACTLY the right spot (which is near impossible) - I cannot get sound out of one or both tweeters.