John, I had this problem of a lot of carbon dust and then the motor failing (after 5 years). The solution was to take out the motor and have it rewound. Prior to that I had discovered (after 3 years) on taking the boat out of the water that the vetus propeller was down to only one blade (all the others had sheared off over time) and I think that using the thruster unaware of this may have caused the strain on the winding. It hasn't happened since (another 4 years) although I noticed recently that I am now short one blade.
It sounds like a jam to me.
If you can reach from water level, from a pontoon or dinghy, isolate the motor electric feed, and stick your arm in and see what you find.
The other way to check if the gearbox and propeller are free to turn is to disconnect the motor cables, and the four holding down bolts them lift the motor off the coupling. Take care it's heavy. Then try to turn the gearbox coupling by hand, to should turn easily and you should hear the water "swishing" as the propeller turns.
If the coupling will not turn, then you either have a jam or a damaged gearbox. If it turns ok, then see if you can rotate the motor shaft, if solid then take motor to a rewinds specialist who will repair it.
Hope this helps.
A frequent "fault" with the 12512 is the blowing of the thermal cut out but assuming you have a green light at the control then it has not blown.I
So my only other suggestion is to track that you are getting 12v throughout
But again, if you see sparking inside the motor then you probably do.
Sorry, not much help.
What year was it fitted? Some do produce a lot of carbon.
The following user(s) said Thank You: John Stollery
Vetus bow thruster 12512 - diagnosing the fault... I was busy dodging Le Boats and a load of weed when it failed so I don't remember exactly what happened. I have far too much carbon dust around the motor, which doesn't turn. the 5amp fuse is OK. the two solenoids (L & R) move when switch in wheelhouse operated, BUT I thought I saw a spark or arc somewhere under the solenoids so suspended those tests.
Is there a diagnostic trail to identify the fault?
It could be something jammed in the tube and propeller region, any way of confirming or eliminating this possibility without divers or lift out (seems logical to be able to disconnect the motor and try to spin the drive shaft).