Originally Posted by Richi
You would need to isolate the send pots from the summing buss by using a basic emitter follower or an op amp buffer, you would ideally also isolate the output with another buffer. Each send channel will also need to be summed before leaving the mixer.
So you will need a reasonable knowledge of these circuits to attempt it properly.
Also from memory the original FX loop on the Bozak suffers from a impedance miss match, if you engage it you will loose some HF.
Search the forums, it's all here and been written about in detail.
The Urei's FX loop from memory is buffered.
Personally I wouldn't bother, it's a classic mixer. I kept mine as close to original as I could. But then I have the same views with regards to classic cars
Re front panel I think few people on here should have either new ones or old stock they could sell you.