annoying squeak

[Ryoken]

my shed is playing up , , I'm just throwing this out for you guys for your opinions
I'm getting an annoying belt squeak , replaced. new serp belt and tensioner,. still squeaking,
removed AC belt , fired it up , still squeaking so its not ac belt or pulley side
checked WP seems ok no play ( 3 months old)
alternator , spins free, no play (1 year old)
PS pump , seems a bit notchy when you turn it but no play but sounds noisier on rotation than the others (17 years and 160k miles)
you can start it up , its quiet. rev to 2k , it starts,. then it squeals from then on
going to go and try firing it up after work (which will annoy neighbours. as it will be 06:30 , and ive got a X pipe on it
ill turn the wheel L to R to see if it alters
ive sprayed wd 40on the belt and it stopped squealing , but ive tried 3 different serp belts by 3 different companies and I'm certain its not belt or tensioner,
ideas?