Those switches are not expensive. I would change it anyway
Just be careful.
The switch concerned is right next to the brake light switch. One is Normally Closed and the other Normally Open
I think that the brake light switch is normally closed and is held open (i.e off) by the brake pedal. Please check though - I labelled my spares and locked them in the foot locker - no time to find them and check now.
My hypothesis is (as yet unproven) that the ECU signal that the switch operates is very low current - below the wetting current of the switch which, in time, corrodes and becomes intermittent,
