Jack,
I do not know if the FETs are factory or not. The screwdriver adjustment for d-c balance is in the screen circuits which is likely not connected to anything in these adapters. That will cause it not to work right. The value of this pot depends upon the s/n. That could explain the difference you see.
12AU6/As are not hard to find or are expensive. The heaters of these are in series to the 100V regulated supply. If any are removed, no heaters will come on. To check for the other 12AU6s coming on, look to see if they light up when the tracer is on. Heater pins are 3 and 4. If no heaters of these are lit, the tracer will not work right.
If you get 12AU6/As, check them for gm then get the ones that are close together in gm for the pairs in each circuit. This makes balancing easier. No need to buy 'matched pair/quad'. A seller on eBay, 3d_electrical, has two quad sets of GE 12AU6s. I have dealt with him in the past and is great to deal with. There are others who have them as well. Do NOT use 12BA6! These are super-control types, not sharp cutoff. The BA6 type is used for r-f/i-f amplifiers in a-m/s-w radios. Getting the 12AU6/As should get your tracer working.
Mark
