THE TOP RIGHT STAIN
As you can see this is a close-up of the stain that appears to the top right-hand side of the code page. The stain was 'peeled' back using citric acid, what that does is to remove the lighter coloration leaving the darker markings visible. At the moment this is the best resolution image I can get. I rotated it to show what appears to be sets of numbers reading from left to right.
CAPTURED SOE CODE
I have another image to show, apparently it is a code captured by the Soviets and was photographed showing some of their efforts to decode the strings. Notice how in one number set they made use of a + sign: