If you're keen, you can take the backplate off the wiper motor and clean out the 500-year-old grease...
Little hints : the motor can be reassembled two ways. One way it runs backwards. Mark the shell before disassembly. Also note the ballbearing on the end of the shaft inside the motor. The brushes and their springs are a faff if they ping out. Trap them with bits of wire. The teeth on the worm drive are sharp. I got a "manatee run over with an outboard motor effect" on my finger when I ran my finger over it.