If your buttons are sticking occasionally, you can refurbish them using Novus Plastic Clean & Shine. Push down on the white tabs and pull the button out of the black casing to remove the button top from the shaft. Then, you can clean dirt out of the button that can cause sticking. If the button still sticks, you can use Novus Plastic Clean & Shine with a felt polishing bit attached to a Dremel to smooth out the plastic parts of the button that contact the casing as well as the casing itself.

If your screws are missing or rusted, these are the exact replacements you will need:

• Top monitor glass metal piece screws - Truss head black oxide M4 0.7mm thread pitch 20mm length screws [1]
• Plexiglass marquee screws - Truss head stainless steel M4 0.7mm thread pitch 12mm length screws [2]
• Smoked plexiglass EQ meter cover screws - Truss head stainless steel M4 0.7mm thread pitch 8mm length screws [3]
• Control panel plexiglass screws - Button head hex drive stainless steel M4 0.7mm thread pitch 10mm length screws [4]
• Center speaker plastic side screws - Truss head stainless steel M4 0.7mm thread pitch 20mm length screws [5]
• Plexiglass how to play screws - Truss head stainless steel M4 0.7mm thread pitch 12mm length screws [6]
• Black side plastic lamp cover plexiglass screws - Truss head black oxide M4 0.7mm thread pitch 20mm length screws [7]

Note that both the marquee and smoked EQ meter plexiglass screws come with metal spacers in original cabinets. I haven't found a good replacement for these yet but as long as you don't massively overtighten the screws the plexiglass is in no danger of cracking.