Ikegami: Bsf-300 Manual
This indicates an unstable external reference. However, if the external reference is fine, the internal VCXO (Voltage Controlled Crystal Oscillator) has drifted. The manual requires you to verify the external reference level is between 0.5V and 2.0V p-p. If the level is correct, the VCXO tuning voltage should be between 2V and 8V at test point TP-5.
It handles 1080i/720p HD formats and can be configured for multi-standard operation. ikegami bsf-300 manual
How to find the official manual (recommended steps) This indicates an unstable external reference
The BSF-300 is prized for its compact 1.5RU (Rack Unit) size while maintaining high-end broadcast features: Signal Support: if the external reference is fine