96' Sentra GXE intermittent wiper problems. please help

[bB2NER]

The wipers work normal in low and high speeds. The intermittent part doesn't. They stop at the top then next cycle they come back down. Kind only half cycles instead. Plus they are hard to shut off in the down position. It takes a couple tries and they never stopp all the way down.I'm gonna first try swapping out the switch. If that doesn't work would it be the relay/amplifier or the motor itself? I'd hate to buy un needed parts.I'm leaning toward the relay/amplifier but that is the only part I would have to source from a dealer. Thanks much in advance, Jeff