I'm just starting to work on this, but in my opinion E does NOT = 1. If it were 1, then the whole first line would be SOE.
It has to be either 5 or 6 because if it were multiplied by itself, it would end in the same number (e.g. 5x5=25, so you write the 5 in the e spot and then carry the 2).
I'm not a mathematician, but I'll think more and try to get back to you.