Yes rear tamper switch , do you have pebble dash etc on the wall, or bell box is mounted on an uneven surface , the only way you can adjust it is by bending the metal switch lever , but you have to be careful when mount back so it's tip isn't catch the wall as it should be still be flattish against the wall
Some bell box's have an adjustment screw , I am sure this doesn't
No dont disable tamper , pointless having the box then , just fix how it's mounted
The side screw is what pushes the switch