Elektronika MK-61 dead digit :(

[Druzyek]

In 2003, I added an Elektronika MK-61 to my collection and used it occasionally for useful things for a few years before it went into a box for the next ten years. When I put batteries in it today, I noticed that the first digit and minus sign no longer work:
   
I took it apart and saw some gunk on the back near the side of the screen that stopped working:
   
There are no capacitors anywhere near there that could have leaked. One time, a board I made worked fine for a few months before malfunctioning, and the culprit turned out to be left over flux. That board worked again after I scraped the flux off, so I tried to carefully carve through the gunk between the traces on the MK-61 but it didn't help.

The only other thing I noticed is the white blob on the lower left of the display in the picture above. It covers two of the five wires leading into the display, as well as some of the traces. Of course, I would be very, very hesitant to start scraping at it, but I did notice that none of the other pictures I have found show anything similar:




Maybe they made minor changes to the manufacturing process over time or it's a repair that happened to a defective display before it was put in the calculator or something.

Any ideas how I can get it running again?