Series One 100 - Horrible squealing noise

[steviebabes]

Hi!
I have a Series One 100 that has developed a horrible squealing noise. I thought it might have been in my Effects chain, but it happened yesterday with only a guitar plugged straight in.
There is a fairly quiet click, then the background noise steps up in volume, and about 5 seconds later the squealing begins.
I have had this problem for a while, but it seems to have gotten worse recently. The amp has always been prone to picking up electrical noise, and quite often with high gain it will pick up the PA from the next rehearsal room using a single coil guitar pickup, switching to humbucker usually but not always stops it.

Yesterday I did reseat all the valves and try and clean the send return loop sockets, to no avail.

I'm hopping this may be as simple as replacing a valve or two, I last changed the preamp and rectifier valve about 2 years ago.

It was looked at by the repairer for the dealer in Stevenage, last year but didn't fail while it was on his bench.

I did manage to record a video where the noise happens and can add that if it will help remote diagnostics...

I've got an important gig this Friday, then 13th, 28th Sep and 5th October, so need to get it up and running quickly.

What's going to be my fastest resolution?
I'm not that far from the factory if bringing it in is a possibility.

Thanks in advance.

[illini]

I had this problem with my Series One. Pull the guts out of the head box and you will see a few plastic quick connectors. They are supposed to push and click together. One of mine had come loose during shipping. Once I pushed it back together the amp has worked as it should for the last 2 years.