Trying to repair a Smith-Corona letter quality "printer"

I picked up a Smith-Corona Memory Correct 400 Messenger typewriter at Goodwill last week. It has the daisy wheel but no ribbon. I debated getting it since I already have enough retro stuff around the house, but every single time I?m at a Goodwill I look at all the typewriters to see if they have some kind of serial or parallel port. This one has a DE9 connector on the back which can be connected to a computer using an external box called a Messenger Module, which I also have. I plugged it in at the store and the typewriter didn't power up. They gave me 10 bucks off so I couldn?t resist and bought it. I?m hoping it?s an easy fix, but I can?t figure out how to get the thing apart at all! The four screws in the bottom just hold the plastic case to the metal frame, and removing them didn?t allow the case to come apart. I can?t figure out how to get the two plastic halves separated. There's no screws in the top and no other screws in the bottom. The plastic halves aren't welded together around the outside, I can wedge a screwdriver between them all the way around. There seems to be something holding the halves together near the four corners. Does anyone have any idea of how to get this thing open (without breaking the plastic)? I?ve searched all over the internet but I can?t find any scanned service manuals. The typewriter is from 1984 and was sold for $600 new so it doesn't seem to me like it would be a "disposable" item so there has to be a way to open it and service it. From what I can tell the 200/300/400 all use the same case, and the Memory Correct II/III use a very similar case, so info for any of those may help. I posted an album here: http://imgur.com/a/SxfTE and a YouTube video here: http://youtu.be/ryDl0Qvl7Gk Any assistance in opening the case without breaking it will be greatly appreciated! :-) -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com