There is a negative temperature coefficient resistor/filament dropping resistor used in the model 52-940 AC/DC set. It's rated at 100 ohms, but I believe this is a resistor that has a cold-hot resistance-also known as " globars". I've read elsewhere that the CL-90 inrush current limiter is the replacement for this. What are the correct replacement options?
Just a suggestion. I have never tried it. If the globar is open replace it with a 100 ohm 10 watt resistor and add a CL-90 in series with the On/off switch. Another possibility is to replace the 35L6 with a 50L6 and do away with the 100 ohm globar and still add a CL-90 in series with the on/off switch to prolong the life of the tube filaments.
I have used a CL-90 in AA5 sets without any original surge resistor protection eg. a Emerson 503. It drops 4-5 volts and increases warm up time to about 30 seconds. In general I usuallly add a CL-90 to all the sets that I restore just to prolong tube life. It's kind of neat to watch the pilot light ramp up to full brightness.
Mount the CL-90 so there is as much clearance as possible to other components, particularly electrolytics. CL-90s get hot. That is how they work. Mouser has CL-90s and does not have a minimum order charge.