The hole in the battery compartment does nothing, the holes circled on the back of the unit are transport mount holes, there were screws in them to stop the turntable jumping about while in transit from Japan......i dont know anyone who ever used them.
Some people think you have to remove the screws underneath the unit (X4) but you dont. The only screws needed are the two at the very top corners (rubber mounted)
If you use my strip down manual for anything, i suggest cleaning the cassette spindles (helps with the APSS system)
Kev