I have an OLD furnace. 1960's Richmond. No electronics. It's not firing up. I've replaced the thermocoupler and the 24Watt trans former. I fear it might be the gas valve itself. Is there any trouble shooting for an old Robertson gas valve?

On old units like this, if you get 24VAC across the gas valve and it doesn't open, you either have a bad thermocouple or gas valve. However, there could also be a high temp shutoff that may be tripped. Look for that too. Honestly, by the time you spend $$ to repair something of this age, you should consider a replacement unit. Even at 80%, code minimum, you will find is saves you a lot of money quickly.