Hi, You need to remove the QR sticker to reveal 4 screws holding the plastic housing and stepper in place. Once removed you will find 2 screws holding the switch in place. John

I have found parts on Amazon where you can adjust the belt tension with a knob. They go in place of the roll at the end of both the X axis and the Y axis. You may want to have a look at those, I can highly recommend them.