The tech at the justanswer website is incorrect. If the pressure switch sticks in the full position the timer will continue running however the washer will not fill, it will agitate dry, the pump will come on normally and it will not spin at all. The fact that messing with the timer knob makes this problem go away temporarily, makes the timer suspect but it may be coincidence. I would replace the pressure switch first and see what happens, but there may be a problem with both the switch and the timer.
Eric