401 brake light switch adjustment?

[Michael English]

Is there any?

My brake lights only come on after severe pressure on the pedal. Crawling underneath I find a stiff wire hook going to 2 spring hooks, going to the switch. The switch works well by finger, but there is a tiny bit too much play it seems. I can't see the other end of the wire from below but assume it goes to the brake pedal.

To adjust it properly, what do i do? Is it from above with a floor & seat out job? Or a rather un Bristol bodge from underneath, a rather hit n miss attempt at shortening the wire hooks?