No power (revs) under load

[bonaire]

I have a volvo penta 30. Which has worked perfectly well for the last year. I am now experiencing no increase in revs above 1000 under load, so the engine sounds ok the propeller is turning but the revs and power (speed) do not increase under load when I increase the throttle. In neutral I can achive 3000 revs. I have cleaned the prop and changed the fuel filters, to no avail.

 

[sandkicker]

Possible spun hub on prop... needs a repair.