Sears radial arm saw - digital readout problem

My old saw is playing up.

Just fixed the carriage bearings.

Now the digital readout is not working properly.

The screen lights up and I can select the different modes. Eg rip elevation.

But the readout just stays on zero when the saw is moved.

I cannot find a common point except the circuit card.

Have changed battery and used a power supply to eliminate voltage as a problem.

The circuit card has a single chip. Marked with several numbers.

Which number is the likely part number to use to try and get another?

M14815668C

47C220AF4564

8848H.

Or is there another possible single point fail?

I only have a small multimeter to probe around with.

So any help appreciated.

Lyle.