Thermoquad ballast resistor question

Maybe someone here can help me...

I have a rebuilt Thermoquad 4-barrel (original equipment) on my 73 Dart Sport 340. I've been having idling problems on cold mornings (won't achieve high idle and loads up and sputters when you first take off). My garage said the ballast resistor for the choke is shot and needs to be replaced. I've looked high and low for this resistor and no one seems to a carry it.

Anyone here experienced a similar problem? Do you know of any supplier who might sell this ballast resistor?

Thanks in advance for your help!

P.S. -- I just spoke to a carb shop that said there's no such thing as a ballast resistor for the choke on a TQ; he thinks the problem might be with the choke pull-off. Does this make any sense?