Just an update, if anyone can help me out that would be great.

I recapped and I am no longer getting freezes but I think I have finally isolated the actual problem, the synth is not freezing and is operating fine unless the audio cable is plugged into the either mono audio outs or phones jack, when I do this it will freeze pretty much straight away or after two or three seconds. 

The moment I put the audio cable in it freezes, signal is giving a buzz. I think I am shorting the whole synth when the audio cable is inserted. Now it looks like someone has previously done something funky to jacks. My phones jack had broken away from the chasis so I just took it off and will replace it. If anyone has any clues from looking at the wiring of what it could be thats shorting it out. There are a couple of resistors bridging on the mono outputs. The brown wire has tape around it and has been put out of use. The black ground is going to the headphones along with a yellow that is bridged across by a piece of metal.

Was anyone aware of this mod? something might of gone wrong with mine..