Wiper blades not retracting when turned off

I have a 2002 Toyota Avalon with a V-6 motor, about 90,000 miles on the car. The wipers work when turned on, but the intermittent feature does not work. The main problem is that when I turn off the wipers, they do not retract. So, I must exactly time when I turn them off so that they are at the lowest point in their cycle to the base of the windshield. Any idea what the problem is here? Thanks!

Rich D, Mays Landing, NJ