4" Tangbands damaged?

I have two 4" tangbands. The other day I saw that one is "pushed" almost all the way in, and the other almost all the way out.

They can stille move (and seems to play fine), but it seems that some DC from the amp is triggering this. The very strange thing, is that it does not help removing the cables from the amp. What could have caused this?
 
Were they like this from the start, or did it develop?

dave
it wasn't there to begin with. I have just made some adjustments, and then I saw it. I have been playing around with some different amps, and one amp (class d) began to oscillate (NXD8950th based amp). It happend at night time, so I discovered it after several hours i guess. I didn't notice then, but it could have happend at that time.