Hi John,
Thanks, as far as I can determine (with lots of research), is that the Ia wasn't outfitted with the AN glass, if I have the wrong information, please correct me! The main difference between the Ia and the Ic (aside from the AN glass and the lens) is that the housing itself is attached, as in not able to be tipped back to better, and easily insert the negative carrier. In any case, I've managed to replace the old cord without any problem; I've got a new bulb in there (a very, very, very, old one was still attached) and the machine runs!