[Milsurplus] Alignment of tube tester I-177

[Wim Lakeman]

Dear Listers,

Recently I obtained a I-177 tube tester.
I think there is a problem with the alignment of the tester.
At the line test it is not possible to get the meter pointer exactly at the
line test postion of 1500 microhmos, even with the line test adjustment knob
rotated full clockwise. Maximum postion is about 1200 micromhos. In the
power-off stand the meter points zero.
Is there any hidden alignment knob in this tester?
Any suggestions to solve this problem?

Best regards,
Wim Lakeman