[Amps] Ameritron AL1500 help

[Edward Seeliger]

I have an Ameritron AL1500 in which I have replaced the QSK board. After replacement, the amp appears to work as it should EXCEPT that the grid current meter reads backwards (deflects down). I can key the amp with increasing drive and get increasing output (I did not move the tuning controls when I replaced the board and it tunes/loads as it should). 

I have verified all my connections are correct to the QSK board and all resistance measurements are as specified in the QSK board documentation. I have spoken to Ameritron twice - the last time they suggested to check the grounds to the QSK board - I have tightened the screws holding the board to the pillars that support it above the capacitor bank and resoldered the coax grounds to the board. They also suggested to check that the blue wire behind the power on switch attached to the terminal strip the fan wires attach to is grounded - I tightened that screw also.

But the meter still reads backwards (deflects down).

Have any of you had a similar problem - any suggestions as to what else to look for/fix.
Thanks in advance for any and all help!
Have a great Holiday season!
Edd - KD5M