Hi - I know this is an old post but thought it deserved a correct answer as i'm sure many people would like to carry out their own repairs without huge Bills. Unlike Spider III the IV version has no screws on the sides. Here is the method to release the amplifier and brains box. Remove the 6 black screws from the top of the amplifier cabinet, these are securing the unit. Remove the 2 front (Top) corner protectors. OK - You'll notice that the unit is still firmly fixed to the cabinet ! This is where we all get stuck and are told to do various things like undo all the bolts & control knobs, remove speaker grill or vandalise the box ! Not so, there are NO concealed screws, torc bolts, hidden plates of magic catches. Quite simply, the metal front panel is part of the amp unit (not the cabinet) , the top of the panel is folded in flush with the roof of the cabinet, this is where the top screws anchor the front and most importantly - In 9/10 cases this is also glued (probably to reduce vibration) The best way to release it is to use two normal table knives - one as a lever the other as a cutter. starting from top left gently slide one knife between the top of the front panel and the cabinet and lever until you have a small gap , then carefully clear the glued sections. repeat this along the whole length of the panel. once done disconnect the speaker wires and the unit will slide out through the back of the box. On re-assembly it's up to you if you glue it back ! Hope this helps.