Tuning half stops on a Williams Universal 12

[Bensmithguitar]

Hi Everyone,

I hope you can help. I've got a couple of levers and pedals that have half stops (I think!) where they raise/lower one string for part of the movement, have a stop half way, then move another string for the second part of the movement.

The trouble I have is that a couple of them are a bit 'spongey' and don't really stop very well on the half stops. Does anyone know how I can tighten them up so they're a bit more solid. I've attached pictures of the end of the guitar. Do I need to adjust any of the hex screws? (Circled in the picture)

Or an I looking at replacing the springs on the other side? I'd like to sort it out if I can.

Thanks!