I have never seen a miller this old. It says Airco 200amp Hornet Special, model 2ddglmbc, sn e3736 c7. It has what I think is a continental 4 cylinder water cooled engine with updraft carburetion. I am guessing and have been told that it was probably built in the 50's. Probably weighing well over 1200lbs... The armature has two large brushes for the welder and only one small brush that I think is for field excitation, which is the circuit that I think has the problem. I have been trying to track down the connections, but when it was built there was no thought of using different color wires.....so...they are all the same color..black. I am not even in the least predujudice, but I sure wish they had used more colors... Any guidance or help will be greatly appreciated..Thanks for the help so far...I will check out the miller site also..