Even with the manual, things go wrong. Here is a cheat sheet derived from the "Troubleshooting" section of the Sony LBT-D507 documentation.
The LBT-D507 uses specific speaker terminals that accept bare wire.
To maintain high-fidelity audio, the manual recommends specific cleaning intervals:
Sony maintains a legacy support page. Go to the official Sony website, navigate to "Support" > "Manuals & Literature," and search for "LBT-D507."