Troubleshoot this weird car problem

[tw]

Originally Posted by SteveDallas

No. It fixes itself once you turn off the wipers.

If a gear inside the wiper motor was stripped, then home switch would occur when wipers were in different locations.

Other 'gear' would be a shaft that connects wiper blade arm to 'rotating back and forth' wheel. If that was slipping, then wiper arm would stay just as far from home position as wiper arm has overreached left side. IOW you could move wiper blade back to a home position manually.

I am assuming you have a Ford blade arm - did not buy a new wiper blade holder because you bought some third party (Anco, Trico, etc) wiper blades? Sometimes these third party blades are not the right size - but close enough for the Pep Boy, et al customer. (If using Ford blades, then blades would not be replaced so often - saves money.)

That leaves something shifting in the arm(s) that connects wiper motor to the 'rotating back and forth' wheel. For example, go to where wiper blade arm attached to shaft from that 'rotating back and forth' wheel. Is the nut on shaft beneath that wiper blade arm still tight? Turn on wipers with ignition switch until blade is partially across windshield. Stop the wipers half way using the ignition switch. Now, grab the blade arm at its base. Is that shaft (through car body) firm or can you shake it?