[R-390] AGC investigation, one very bad part

[Alan Victor]

After looking at the open AGC loop behaviour and the schematic, it became
clear something is wrong in the bias string setting up the AGC reference
voltages. That coupled with some resistance measurements leads to *R544*.
Its value nominal is *2.7 Meg*, measured *327 K*.

This really upsets this string bias current, the voltage divider and the
subsequent AGC voltage points when the loop is   closed. I'm sure there are
more culprits, but for now its electrical is reasoanable. There are now
more mechanical issues then electrical,  so a clean up is in the works.

Thanks,
Alan W4AMV.