I agree, fill it up and walk away. That is a nice original machine with all original parts, I would be very confident that it is set up properly.
Keep in mind the upper fan is used to keep temperature constant, if it spins slower than your new one add a few drops of oil down the shaft.
You also have a very cool coin mechanism, obviously one of the earliest produced with not many parts that could go wrong.
When you remove the slug rejector you will see a very simple operation.
Nice machine!