Hi Morten,

If memory serves me, does not the shoot again light activate when the magnet grabs the ball?
If so, then a 6.3 V extension, in the form of a strip could be placed in the outhole to go with this.
If not, Others will post help too, to tie off magnet....

Use a reed switch.

https://www.sparkfun.com/products/8642

GI~ -----> Reed Switch -----> LED Bulb -----> GI~

Solder a wire from one side of the wiring GI to one side of the reed switch. Solder the other side of the reed switch to one side of an LED bulb (preferably an AC/GI bulb) then solder the other end of the bulb to the other side of the GI wiring. (You can just tap off a GI bulb somewhere near the magnet).

Zip tie the reed switch to the magnet. Each time the magnet fires, the reed switch will close and that will complete the circuit, lighting the bulb.

If you want to get really fancy you can buy a PIG II from www.dkpinball.com and make the light fade, pulse, blink, flash, blow a horn, whatever. But it's a bit expensive for a single mod.

This game really needs to let you know the magnet is active somehow

I was thinking of doing the same thing myself but never got round to it

I don't understand. The magnet doesn't sit there active while the ball is bouncing around the playfield. The magnet senses the ball and activates all at once. It's like the Metallica magnet. The light would come on only when the ball is being saved. Isn't it obvious enough that the ball is being saved since it gets flinged up and doesn't drain? You need a light to come on at that moment also?