McIntosh C-27 panel lamps

Does anyone know how many panel lamps there are on a C-27 preamp? The service manual says there are 4 but I can only locate 3! McIntosh Labs customer service also says 4 but couldn't tell me where to find the 4th one. If anyone knows if there are 4 then could you tell me where they're located please? Three are obvious and accessible once the top panel is removed but that phantom 4th one has eluded me. Thanks

 

Never mind! I finally found the 4th panel lamp - you must remove the front panel to get at it!! Located on the far left (facing the front) at about the midway point vertically. Completely enclosed in a metal "box" that splits the chassis main sheet metal surface. The power wires feeding it come from the leftmost visible lamp socket but are also hidden behind the front panel. Attached a pic in case anyone else needs this info (hard to see it but I highlighted the area in the pic).