I normally leave my boat without ballast in so that it sits higher in the water and keeps the white line cleaner, so I possibly use the pump more that others. When I came to empty the tanks after my first sail of the season a couple of weeks ago, I switched the pump on and was surprised by the complete absence of any noise. Tried switching everything off and on again as you do, but still nothing. Assumed that it must be the pump electrical connectors corroding over winter, but no, they were fine. Took the whole pump off and removed the impeller and found that I couldn’t turn the motor shaft, even using pliers to grip it.
Took the whole thing home and stripped it down to be met with quite a mess inside. Top bearing rusty brown and completely seized, bottom bearing just about moving but not good, thermal cutout switch open-circuit and the interference suppression capacitor wandering around loose because both terminal legs had corroded through completely!
On consulting the manual I noticed that it advises that the unit should be mounted with the pump head below the motor, whereas in my 26 it has been installed the other way up. This means that when the shaft seals loose their effectiveness then salt water will start leaking from the bottom of the pump, down the shaft and into the motor, hence the damage. In hindsight this appears rather obvious, so when I put it back I’ll be mounting it the other way up, which will probably require a mod to the plumbing, and possibly a reversal of the pump direction (it pumps both ways).
This post is therefore an advisory to everyone with a ballast pump to check which way up it’s been installed, and to turn it round if the pump head is currently above the motor.