Stark 9-66 tube tester - repair help

Hello everybody! :)

I have an old Stark 9-66 tube tester (Hickok 533A clone) that I wish to repair. I own it since 2 days so I know a little about it. I did some research on the net and found very good info on this website -> pacifictv.ca, here's the schematic http://pacifictv.ca/schematics/stark966schematic.pdf

The problem is that I can not properly adjust the "line level", I hold the P7 button while I turn the "Line adjust" knob, the needle is going right and left but far below the expected center spot.

I would really appreciate if anybody have some suggestions that could help me.

Thank you!
Mike

Edit:

I found the problem, now 100% working..
 
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