[Kenwood] re TS-940S alc/pwr problems

[Fern]

       I have been working on a recently acquired  early production TS-940S 
(serial #5110XX) . I corrected a poor receiver sensitivy problem with 
re-alignment but the transmitter had low  or non existent alc reading plus 
intermittent output power(15 watts only). I had to replace two of the 
lithium batteries to get the memory functions to work and while I had the 
front panel loose, the radio suddently had full power output with lots of 
alc action. When I re-installed the front panel, then the same old problem 
of low power and poor alc came back.
     Here's what I found. A previous owner had installed a diode in series 
with a 15K resistor from a brown wire then tied into one of the rf power 
pots (just behind the front panel) which is in the switch unit X41-1600-00. 
I have done a google search but cannot find any info to do with such a 
modification.
     Any info or guidance on this would be greatly appreciated.

              Happy New Year from Fern    VE7GZ