First, you have already answered my first question: "What maintenance it required on the top mechanism"? Not the top, but the MECHANISM. So, thanks.

Second, I have read a post or two here about the top not raising or lowering - just wanted to know (since I am an electronics tech by trade and know it's largely electronic in nature) what information is available to me if it refuses to work. I suspect most problems are bad sensors that cause it to not be able to complete it's cycle properly - but I am uncertain if that is really the case.

IOW, just worrying about stuff, like I always do with something new!