Actually 2 questions. I have a 2100d carb with an automatic choke. The choke mechanism appears to be frozen. Not the butterfly, but the thermally operated contoller. Where can I find replacement parts?
I've had a similar problem - I originally thought that the choke was gummed up, and it turned out to be a faulty heat riser tube (jury rigged ala the PO). Any chance this is the case? Also, have you taken the housing for the bi-metal spring apart and cleaned everything out real good? I haven't really answered your question about where to find replacement parts, but I hope this helps.
I cleaned up the bimetal strip, etc. but the heat riser is what appears to be seized. The head riser plunger is where it is frozen. This keeps the choke in a single position. IIRC, you should be able to overpower the heat riser and force the choke open/closed. I can't seem to find this sub assembly anywhere.
Is my memory in tact, or should the butterfly be stuck when cold (or warm for that matter)?
I have several of different vintage. Send me a pic of yours and I will match it up with one of my spares. THe piston can be worked out if you soak the assembly in liquid wrench for a while and gently work the push rod with a pair of needlenose.