My washer only fills about half way, no matter where the fill level switch is set, unless I hold the knob in between two positions. I did not check to see if it would overflow by holding the switch for to long, I get it pretty much full and then let go. This is for wash and rinse. This washer is a Centennial, and shows "Commercial Technology" on the front control panel. Is this probably the switch, which has gotten hard to turn "up" lately, or the level sensor, or something else? Any help would be appreciated. Thanks, JT