In early 2025, Linac modulator 3 at the Taiwan Photon Source (TPS) exhibited signs of performance degradation. To reduce electrical stress and prevent an unplanned failure during user operations, BR injection feasibility was evaluated at 130 MeV, 140 MeV, and the nominal 150 MeV. Two compounding mechanisms limit low-energy injection efficiency: increased geometric emittance from the Linac, and degraded BR power supply waveform reproducibility at the earlier injection point on the ramp, which reduces the dynamic aperture. At 130 MeV, the mean BR current of 0.168 mA cannot satisfy the 5-second top-up window. At 140 MeV, a mean of 0.342 mA meets the >0.3 mA operational criterion, and this 140 MeV rescue mode maintained uninterrupted user service throughout the modulator degradation period.

A real-time waveform monitoring system has been developed for the pulsed power supplies in the injection chain of the Taiwan Photon Source (TPS). The system covers eight kicker and septum magnets spanning the Booster Ring and Storage Ring injection path. Two operational incidents involving SR Injection Septum~1 motivated its development: in both cases, waveform anomalies that were imperceptible by visual inspection led to severe injection efficiency degradation or complete injection failure. The system acquires waveforms via EPICS Channel Access, computes shot-averaged deviations from a stored reference, and compares them against physics-motivated alarm thresholds derived from dedicated machine study experiments. The thresholds are expressed as time-resolved curves that directly map waveform error to injection efficiency degradation. The system has been deployed and is currently in operation at TPS.