They updated the PCBs a few years ago to do away with the reset button. It is often the case that the motor takes out the PCB or vice versa. Often times nowadays the only remedy is a full new head, unless like you, you have a few spares hanging around and you can revert back to the reset button type of PCB as you did.
The fix you describe is something we often do with reconditioned machines. On some levels it seems kind of counterintuitive to revert back to an older set up to increase reliability, but that is indeed what we are all doing here.
Dyson no longer supply either PCB. Until they stop making cleaner heads it is unlikely that the aftermarket will step in and solve that one.