It sounds like the crank-arm on the motor has slipped on the splined shaft.
Inspect the linkage at the motor gearbox to see if the retaining nut is loose. If it is, remove the nut and reposition the crank-arm so the wiper is where it should stop, then reinstall the crank arm, tighten the nut to the correct torque setting, which I think is 26lb/ft.
Finally, wet the glass and run the wipers a few cycles then shut off and note stop position.
If your gearbox has a flat on the shaft instead of splines, you are forced to go by the flat for positioning.
2000 Winnebago Ultimate Freedom USQ40JD,
ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy