I've been using my S4 for years and it's always been fine with 2 decks connected to inputs C & D. Suddenly one leg of input D has gone really quiet - almost like the 'pan' knob has been turned. The VU input meters show one input and maybe 4 or 5 times higher than the other. The physical deck is fine - swapping the inputs over shows that the issue is with that specific input connection. Anyone seen this before?
