Pull the mini lever surround trim off the CID - its only clipped in, start from the front nearest the display.

Each mini lever is held in with Torx 10 self tapping screw, remove all 4 screws then lift the mini lever out.

There is 2 x small cross head screw the hold the grey plastic lever part on to the mini lever - these come loose.

Look carefully at the base of the mini lever where the wiring loom plug is connected, you will see a small cross head screw, these also come loose & effect the mini lever calibration as it allows the potentiometer to move, tighten this screw & refit the mini lever.

Try recalibrating it now.