Oil Pressure Relief Valve - What should it look like?

Hi all, the oil pressure light illuminated at tick-over, so I figured I'd better start exploring, the obvious candidates being a loose oil pump bold or the relief valve.

I dropped the sump pan and checked the oil pump bolt which was fine. I installed a new one which included locking compound to help me sleep at night.

I removed the plug from the oil pressure relief valve. The spring checks out fine measuring 42 mm as it should. However, the plunger needed to be pulled out with pliers suggesting it's a strong candidate for the oil pressure warning light. The plunger looks fine.

I thought it would be wise to check the bore of the valve where the plunger sits. The plunger sleeve itself looks okay but it's not looking good above and below it - see photographs. It looks as though there's metal sheared/fractured. Does anyone know what this should look like?

Thanks in advance.