The Von Duprin 4100 Series MaxHold Shearlock is a high‑strength electromechanical lock that uses a shear‑type mechanism to secure cylindrical or mortise locks, commonly installed on exit devices in commercial and institutional settings. Common failure modes for this class of electric strikes include power supply degradation (voltage drop or intermittent supply), relay coil wear leading to incomplete energization, and mechanical wear of the shear pins causing false engagement or failure to release. Initial troubleshooting should verify a stable 120 V AC input with no voltage sag, inspect the coil and contactor for signs of burn or corrosion, and confirm that the lock’s reset and release signals are correctly routed and free from short circuits; checking any associated error codes on the control panel can also pinpoint relay or sensor faults.[oss-gpt-20b]