OK listen close...Once you have removed the 2 screws on the sides and the 2 small screws on the back...Your there! Pull the dam lid towards the back of the unit. The reason its so hard to pull off is because they put glue or adhesive or something to make it sticky. Just use more force I promise you wont hurt anything, there is no big metal lip holding anything just pull it back . You do not have to touch the front faceplate or End caps. You'll get it, just pull it harder it'll come off. As far as tubes are concerned I would replace them all with NOS Mullards (british made) the 12ax7's might cost you $140 a piece but the NOS 12AT7 Mullards are running around $40 and you can get them from Kevin at Upscale audio.
Tube rolling for C 220
Hello, I want to try to use different tubes for my Macintosh C 220. I unscrewed but still cannot open the case. Can anyone let me know how to open the case ? And I would appreciate if you could share your experience with tube rolling for C 220. Thanks.