[HAM] T522 transistors

[Gunter Bauweraerts]

Hi Hugh,
it seems that you know something about Hammond Organs.
I have the following problem with my T522 (just got it last week from an old lady):
while playing there is always a heavy background noice, a rather low hollowsounding noice. 
Could you give me some advice?

Thanks a lot,
Gunter
Belgium