Mechanical RC Speed controller

[Puppetmaster]

Ok ive got a tamiya tl-01, standard mechanical speed controller, how do i completly reset the the neutral position (using the slider on the control doesnt move it enough) as it goes to far one way.

 

[Puppetmaster]

its a bit awkward to take the arm off, gotta unscrew either servo or speed controller so i can unhook the arm, any other way

 

[Puppetmaster]

ok when do i do this, when the car has no power what so ever, when the battery is connected but everything is off, when the car is off but controller off?