We had a representative from HP look at our printer when they were in servicing our other hardware. You failed to make it known that all switches have a small latch on the interior. All you have to do is use a small screwdriver and pull it down before attempting to pull it back into place...thats it.
Im sure glad i didnt follow your "advice" in disassembling our entire printer for something so simple. Thanks for the delayed support, we will be continuing our business relationship with other companies that have the ability to support both their own products better then "here is a service manual, good luck"