Crumar Musical Instruments User Group.

Thanks again Mike for all your help, I got an op amp from Maplin today and.. I have sound.... yay!
The chip I got was an LM741CN, the spec seemed close enough and in any case it did the Job, and all for 95 pence.

It does seem to have a fair bit lower volume output overall than my modern Korg, I'm not sure if this is normal for old synths? However all the voices and the effects work a treat which is the main thing.