Details are provided on FET matching and also the effects of mismatched resistors in the input amplifier circuit on CMRR specs.
A 5Meg linear pot proved somewhat difficult to obtain locally, so an alternative using a dual 2Meg pot is shown.
I used the PSU-8 module for the power supply to both ethe audio (+30/-10) and the meter lamps and relays (+11.5V).
A gain reduction disable module was used to convert the SPST switch on the attack pot to a SPDT switch as required by the circuit.