Since being back from uni I have had more time to fiddle around with my stomp boxes. I have quite an old CS-2 compressor which I tried out, and whilst the pedal sounds fine, it gives off an incredible high pitch noise when used with high gain. My noise gate cuts it out the majority of the time, but I think it cant be making this much noise on its own and that there may be something wrong with it inside?

Anyone got any experience with this sort of problem, that could give me any advice?
A Titan, A Deity

PRS P245 Semi Hollow
Suhr Modern Guthrie Spec
Mayones Regius 7 Buckeye Burl
LSL CVS Studio Strat
Fender American Standard Tele
Faith Hi Gloss Venus

Mesa Lonestar Special
Mesa Mark V:25
Zilla 2x12 Fatboy
Line 6 PodHD500
Wampler, Keeley, Strymon, TC, Xotic, Chase Bliss Audio Pedals
Compressors and high gain don't normally mix. You're boosting the signal, which will naturally resort in feedback, or that high pitched noise.
Gibson Les Paul Studio
Highway One Telecaster
Dean Evo
Mesa F-50
Laney GH50L
Vox AC30 C2
Ampeg V2