The Bei Industrial Encoders KH25D‑SS‑1000‑ABZC‑28V/V‑SM18 is a 2.5″ optical incremental encoder with 1 000 pulses per revolution, EMI shielding, IP66-rated housing and 40 lb ABEC‑7 bearings for harsh industrial use. Common failure modes include misalignment or wear of the optical sensor head, degradation of the shaft seal leading to dust ingress, and electrical contact loss in the 5–28 V input leads; these often manifest as jittery counts or zero output at high temperatures. First‑check diagnostics should verify that the supply voltage is within spec and stable, inspect the encoder housing for signs of mechanical damage or seal compromise, and confirm signal integrity on the A/B outputs with an oscilloscope or logic analyzer before proceeding to replace optics or bearings.[oss-gpt-20b]