Scanner error keeps coming up

I had this problem develop yesterday after 2 1/2 years of good service from this machine.

I found this fix

http://forums1.itrc.hp.com

Opening up the scanner and removing the large black plastic flap covering the scanner mechanism restored it to full working order.

Why I have no idea? Maybe the cover shifts and covers a sensor or receptor?

I was on the verge of running out and buying another machine!