You may be thinking of the board I made for the DC508 counter.
It could be modified (new board) to fit the DC503A, but I would need an original board for the pattern as there are no dimensions in the service manual.
If it is just one LED display digit that is out it should not be too hard to remove, the same LED may have been used in other units.
At least it looks like this board has connectors and is not hardwired as some of the older units.
At least the displays used on this unit have the decimal point on the right side rather than on the left, so it may be possible to find a off the shelf replacement.