These step by step "isolating roadside problems in 10 mins" procedure or hotwiring as per these attachments have helped me many times
Frank, you say another wire follows the high tension lead from the coil to the upper plate??? I don't believe there is such a wire on a stock Model A setup.
If one end is screwed to the upper plate, that is a ground. Where is the other end attached?
Pics of your battery and its connections, your junction box etc. would help.