The wiper knob is relatively easy to remove, first you need to remove the lock nut holding it, if it is tight you’ll need to use two screwdrivers into the grooves in the nut using each other for leverage, you do this by crossing them over before you start twisting the nut. Secondly with the wiper you need to remove the knob, this is very simply removed by a small screw hidden underneath but on the knob.