I believe that you can solder Mazak.
But this was just adding pickups to the sides of a Mainline 03 chassis, that was a rubbish intermittent runner, going back well over 20 plus years ago.
I presume the 03 chassis was Mazak?
Anyway I cleaned up the sides, just enough to where I wanted to solder to.
Tinned the Mazak with a Bakers Fluid type flux and low melt solder.
Cleaned the area thoroughly to get rid of the flux with washing soda, several times, thoroughly drying between applications and making sure it does not get into the motor ect.
Tinned the Phosphor Bronze pick-ups with 145 degree solder and flux paste.
Fluxed the two and soldered them together after adding more flux. (9% Phosphoric Acid).