Pure paranoia.

You are still missing my point, IF this is a PC based product then it is designed to run one thing - a pinball machine - that's it, nothing else, NADA, ZIP, diddly squat.
Therefore maintenance and product life comes into it. We are still maintaining pinball machines now with the boards you and others produce, coil sleeves, coils etc. the list goes on.

Absolutely NOT! This is my entire point. I'm not getting personal - it's FACT....

If you fit one of my boards, you screw it into the machine, plug it in and away it goes - JOB FINISHED.....to replace a motherboard you need to install all new SOFTWARE drivers (that suit the new board) and probably replace RAM, micro, power supply etc etc  -

This is VASTLY different to repairing an embedded pinball and will likely be beyond most people.