Thanks for the quick reply... I believe the screw is underneath part #9 on the diagram you sent. And I think that to get that part off, I need to remove the impeller #11 by removing the nut #12 on top of the impeller. I have looked at the diagram you sent, and I assume that the nut #12 holding the impeller on is just an ordinary nut and can be removed. My main concern is in not creating more of a problem by disassembling something I shouldn't !
Tried to use a magnet tool to get to the screw, but it is too wide and doesn't fit between the drain "fins".
I'll take a look at the service manual you linked, thanks for the info.