Peter, the circuit is a bit more then those few resistors. The
hang time and the decay time are separately controlled by
signals from the latches in 4042s U4 and U13, you need to check
that they are sending the correct control signals to the switching
transistors Q2 and Q19 and the 4066s U11 and U12.?? It looks to me
like something is not switching when it should.
I was sorting some 1792s recently that had AGC problems and found
sending a string of short CW pulses from a signal generator a
great help in fixing them.?
73 - Dan
ac6ao / g3ncr