Hi I'm about to crack open my Beomaster 4000 for the first time to do cleaning it was very dirty outside I'm sure its worse inside. What things checking and what needs maintenance. Where should I start? It has very scratchy controls and crackly buttons and the balance control has to be moved lots so both stereo channels come in. The Bass control doesnt seem connected inside and won't change the Bass. The lights light up but seem dirty and dim. What oil or lubricant do you use on the moving parts? I piece of vaneer is missing from the edge of the radio,top and bottom. I have the service manual so I can find things and locate parts. Thought or ideas.