Have you managed to get it sorted ??
i just bought an apollo 9 that was faulty. all lights on apart from 12v +
Checked all fuses tested all connections but still the same.
Wipped the psu out and sat it on the bench and reworked all solder joints. All the voltages were correct comming from the main coil. as u say 11v from the 12v line... check the wires to and from each fues holder . Bang there was a bad connection on the fuseholder on the 12v line. all the solder looked good but there was a fault in the fuse holder and the cable going to it.. Just salvaged it from the scrap heap. hope it might help you a bit with getting your machine running again.