Bose L1 model II, starts to squeal occationally
Hi, My Bose L1 model II has start to make a squealing sound occasionally. First when I heard it I was performing quite loud in a bad acoustic venue, so I thought it was some kind of feedback issue. A had this problem since then and still thought it was related to high volume. But the gig yesterday the squealing came at very modest volume. So it can't be that. Do you know what it can be? or how I shall troubleshoot it? It seems I can't make It squeal on purpose. And It also seems like it doesn't occur until a bit in the performance so I guess it has something to do with the electronics in the footer when it gets warmed up?
I could also add that its not a regular feedback sound. It sounds more like its being overloaded, a peak sound that kind of yell so its not consistent. Still no red lamps that indicates that its being overloaded. The system is quite old now and didn't have this problem before.
Where should I start to troubleshoot and how? with the footer or could it be the tower, or something else?