Hi all, I have a JCM 900 4100 and the FX return is not working. I can get a signal out of the send just fine, but if i try to put any signal into the FX return, I get nothing. If I bridge the send and return with a patch cable, when I crank the master volume I get a very low volume, oversaturated signal coming through. Things I've checked: all tubes work fine jacks aren't corroded or broken the FX jacks and the FX pot are soldered fine the FX pot works (I checked with an ohmmeter) If I have a patch cable bridging the FX loop, there is no signal or even any voltage drop between the tip and sleeve connecters of the return jack at all. Does anyone have any tips for troubleshooting, or what could be the cause of the problem?