Alternately, it looks like not much ratio, e.g., about 15 squares of resistance on the long arms, and one square in the middle. So, a differential gain of 1/15 to 1/30, depending on exactly how the fields work out.
That assumes the conductive traces are solid underneath the enamel, and not snaking further.
I can say say with confidence, you aren't going to find this unless it's specifically made available by the manufacturer as a replacement part. Consider replacing the board.
Tim