What comes back up the bore
Most sets arrive for one of four reasons: the winding has gone to earth after water got past the cable entry or the seal; the thrust bearing has worn and the impellers are rubbing; the shaft has seized in the bush after running dry; or the impeller stack has worn and the discharge has quietly halved over two seasons while the current stayed normal. The last one is the one people live with for a year without knowing.
What we do with it
The set is stripped to the stator, rotor, shaft, bush bearings, thrust pad and impeller stack. The winding is rewound in resin- or water-filled construction as the maker built it, the cable entry resealed, and the mechanical seal, thrust pad and bush bearings replaced. Impellers and diffusers are gauged for wear and changed where the clearance has gone. It is refilled, sealed, and its insulation checked wet — not dry on a bench, which tells you nothing about a motor that lives in water.
Tested against head, not just switched on
Anything that spins looks fine on the workshop floor. A pump is tested against discharge and head, and the current recorded, so what goes back down the bore is known to lift what it is supposed to lift. If the bore itself has dropped and the set is now under-sized for the water level, that shows up here — and we would rather tell you that than have you blame the repair.
Panels and dry-run protection
A large share of burnt submersibles were killed by their control panel, not by their motor. We check the starter rating against the pump’s full load current, and fit dry-run and single-phase preventers where there are none. It is a small part of the bill and it is what stops you paying for the same rewind next summer.