I recently received a TOA ML-304B which had some faults. Primarily, the remote relay was not functioning.
The case had a large dent on the bottom near one of the PCB mounting posts. The unit was packed very well for shipping, so this damage was from one of the past owners. The board had cracked at this mounting post, which broke some traces.
I repaired the traces with some wire, and the unit is now 100% functional.