The easiest replacement mistake is ordering “the same red rubber” or “the same black insert” from a photograph. Color can vary by supplier and project, so it is a poor material identifier. The standard flexible-element material for the EVER POWER NM range is NBR; alternatives should be requested by material or duty and confirmed for the operating environment.
Record the failure pattern before throwing the old ring away.
One-sided wear can point to alignment. Local crushing can point toward shock or position error. Surface softening may suggest contamination. These observations do not diagnose the machine by themselves, but they tell you what to measure next.
Confirm the coupling size and hub condition.
Use the model marking where possible. Inspect the hubs for movement, fretting or damage and verify the S gap and alignment before installing the new ring. If the old coupling has no readable marking, send dimensions and clear photos with the shaft data.
