When I knew Blake Patterson, he was a bassoonist and music theorist. He helped me fix two TV sets, and I have since resorted often to his method of repair:
Take it apart. Clean the insides. Vacuum the insides, wipe off dust. Put it back together.
Obviously this system does not deal with tired motors, loose wires, blown circuit boards and the like, but it is remarkably effectve. When you take somthing apart, note what you're doing so you can do it backwards later. If you lose parts, or have parts left over after reassembly, the thing may not improve.