How to open/unscrew a Model M?
The shell of the Model M is held together by four hex nut screws. Three are recessed. You need a nut driver to open it. The proper size is 7/32" and it should have a slim barrel. You can find the correct driver in a Sears.
The proper name of the product is Craftsman 7/32 in. Easy-To-Read Socket, 6 pt. Deep, 1/4 in. drive, model #45815.
This is what it looks like:
Look here for the Sears product page:
http://www.sears.com/shc/s/p_10153_12605_00945815000P?keyword=craftsman+7%2F32
You will also need a 1/4 in. spinner to attach it to. Craftsman 6 in. Spinner Handle, 1/4 in. Drive is what you need. Sears carries it too here: http://www.sears.com/shc/s/p_10153_12605_00943393000P
Whenever I have a need to open a Model M, usually because of something I spilt, I could never seem to find my driver. This meant an quick trip to Sears to buy another. If you don't have an urgent need to open your keyboard and would like a one piece solution, see here:
http://www.clickykeyboards.com/index.cfm/fa/items.main/parentcat/11298/subcatid/0/id/105901
The Model M will not work with my PS/2 port
If your Model M does not work reliably or at all, your PS/2 port may be to blame. The Model M is a device from the mid-to-late 80s, and the keyboard control board and LEDs inside the machine draw a lot more current than a throw-away, el-cheapo modern keyboard use. It requires 275mA, whereas a modern cheapo keyboard may only need 1/10 of that. Some PS/2 ports just cannot provide the current for a Model M to run reliably or at all. I have never encountered this particular problem myself, but according to the link below, it can be found in many motherboards.
There are two solutions to this problem, both are listed on this page:
