Product review (5 stars): Good part.
This is a good factory certified part that came very promptly.  I plan to use Pro-Gold connection enhancer when I attach the wires.  The wiring connectors become intermittent--that is what goes wrong, I think.  The photo sensor puts out a relatively low voltage signal and the control board up top isn't sensitive enough to detect that signal when it weakens, I think.  Design flaw!