Further to my previous message about how to create the Telstar sound, I have made some progress with it. Attached is a photo showing the knob positions I used. It kind of sounds like the original, but its a little too smooth, but I can't think of a way to get a harsher sound unless I stick it through an external distortion pedal. Note that you need a slight touch of vibrato using the mod wheel.
Maybe you could try it yourselves and have a play with it. You might be able to get it closer than I can.
I look forward to hearing what you can come up with.
All the best