Start here — before replacing any parts
Separate an electrical power failure from a jammed or damaged rotor before replacing the motor.
This information comes from a shared HW-series reference; check the UV module, rotor and electrical rating fitted to your HW-304B.
Manual scope: Electrical rating and impeller shaft version
Do these checks in order
Follow the steps below and keep a record of what changes after each one. Stop when an actual cause is confirmed.
With dry hands, check a known-working, correctly rated outlet and the condition of the unplugged cord. Never use the filter if a cord or plug is damaged.
Unplug the filter; confirm that the canister and inlet/outlet lines are correctly assembled and primed as required.
Inspect the impeller and shaft compartment for gravel, broken shaft pieces, debris or a seized rotor. Clean only the intended serviceable parts.
Reassemble the housing completely before restoring power. Do not attempt powered motor tests with exposed moving parts or water nearby.
If the problem is gone
Motor runs and flow resumes after removing a blockage or restoring power: verify steady water circulation.
If the problem is still there
Good supply and a free, intact rotor but no motor action: the HW-series chart does not prove which internal electrical part failed; obtain qualified diagnosis.
Which cause matches your result?
Use these more specific checks only when the earlier steps point to that possibility.
01Electrical power is unavailable
Check whether a suitable working supply is connected without touching wet connections.
Restore a safe compatible power supply.
02Rotor shaft is damaged
Unplug and have the shaft condition inspected.
Replace with a shaft confirmed compatible with HW-304B.
How can I tell it is actually fixed?
Observe stable flow after restart and check the canister and hose joints for leaking water.
Before buying a replacement part
Confirm voltage, rotor shaft and impeller assembly against the exact HW-304B label.
Where this guidance comes from
Primary reference: View the manufacturer or manual reference ↗
Applicability: Electrical rating and impeller shaft version. Source evidence: Matching model owner video plus manual.
The instructions are original English troubleshooting explanations derived from the listed technical facts; they are not a verbatim service manual. Do not apply them to an unverified revision.