Posts: 4,027
Threads: 172
Joined: Aug 2005
Hello, my friend; where have you been? Such a long time we do not "read" from you...
Look at the top surface area over the LCD display. There is a label over there with the HP logo and the calculator's name. If you (carefully) remove it you'll see many (about eight, if I am not wrong) plastic thermal rivets. You have to find a way to unlock them to lift the upper cover.
I have a photograph with an "exploded" (not assembled) HP28S. As I find it I'm sending it to you.
Best regards (some não, meu!)
Luiz C. Vieira - Brazil