Weird audio problem

I hope i can explain this well enough.

My girlfriend had these speakers where only 1 of the 2 produced sound. When we moved in together i decided to take a look at them. I noticed when i switch left and right the alternate speaker would start producing sound. I then fiddled arouns with the balance and noticed that if i put it 90% to the right ( when the left speaker was working) i had a little bit of sound coming from the right speaket, but overall sound would be low volume and uneven. Ive then switched everything out, reciever, cables, aux cable, sound source and even different speakers and the problem would stay. Even the original cables with a different reciever and different speakers would produce the same problem, but other cables and speaker with the original reciever also produced the same problem.. Im really lost about what coulde be it.