AVO VCM-163 Tube tester problem
 

I have a VCM-163 tube tester with a problem - thumb wheel section #3 is broken. Everything else is OK.
One way to fix this, could be to swap the broken switch with section#13 which is rarely used - or any other section for that matter......
I haven't tried to dismantle that thing yet....... it looks rather cumbersome, - which in itself does not really scare men, but is there anyone here who has opened that thumbwheel section? Just wondering if it may create more problems than it's worth????

( Spare parts seems like unobtaniom.... I have tried... or ??????)