Looking for an Engl 620 circuit to fix a possible problem

Hi, I got a used Engl 620. There was a hand made speaker-imitator embeded in it on one of the channel. I simply removed the speakesimulator so it's ok now, the two channels sound similar, good. However I found that instead of resistors that used to be there originally someone put ordinary bridges. And I want to restore the original resistors, but don't know the parameters of them

Here's the pic:

The lower peace inside the left circle is a resistor, while other three including the two inside the right circle are bridges. So the schematic is needed.

Thanks.