As for the hole behind the Logo/Serial Number Plate the later manuals refer to it for access to the switch. This is something I talked about in my Shopsmith Model 10's What When and Where thread. Later Model 10ER's had the version 7 Headstock with that hole and the Plate was held in place, most commonly, by pin at the top and a screw at the bottom. edma194 if you remove one or both of the screws you can rotate or remove the plate to expose the hole. If your Headstock doesn't have a hole behind the plate it is a version 6 Headstock and someone likely replaced the pins that held the plate on with screws. Without actually seeing that the hole is there it is hard to tell if one is a version 6 or 7 Headstock.
Mark V completely upgraded to Mark 7
Mark V 520
All SPT's & 2 Power Stations
Model 10ER S/N R64000 first one I restored on bench w/ metal ends & retractable casters. Has Speed Changer, Model 4E Jointer, Jig Saw with lamp, a complete set of original accessories & much more.
Model 10E S/N 1077 oldest one I have restored. On bench w/ metal ends & retractable casters.