Some excellent radio-repair books are listed on my page Books for Radio Collectors . Your public library may have these, or they can be ordered from your local bookstore or Antique Radio Classified . Commonly needed electronic components are readily available. See my Parts page. For the most common repairs, you need to be able to read and to do simple soldering.
Old radios carry high-voltage current that can cause injury or death.
The repair books explain how to do this work safely. Many radios can be repaired using the general techniques and information given in the repair books. Some problems do require specific information, however, and the schematic may include other useful facts, such as the date of manufacture. Schematics for US and Canadian radios typically cost a few dollars and can be ordered from the sources in my Parts page. One of the most common misconceptions about radio repair is that you should start by replacing tubes.