[morzh]

I took the resistor board out. Too involved and teathered, with too many stubs to unsolder to handle it while still not fully free.
   
   

I still use parallel resistors to remedy those that do not exhibit signs of deterioration and simply drifted up a bit more than acceptable.
This one is 2M.
It drifted to 2.7M.

I needed to put 8.5M in paerallel. I had a bunch of 4.7M resistors from a kit from mAmazon (their tolerance more like 10% vs promised 5%), one being 5.7M....I put two of the lowest values, 4.65M in series, in parallel to the original one and got some 2.1M.

   
   

Then I will need to clean the board. Grimy as a tar pit.