What's the matter with my boiler?!?

Oilfired 'Eurocal' failed this morning after making noises for a day or two (I thought it was air). Have pulled out the burner to find that the fan (on the other end of the motor shaft to the pump) moves freely about 5-10 degrees then becomes heavy to turn. I assume that the free bit is play and the heavyiness is caused by drag from the pump. When powered up, the motor doesn't run, but does give an initial twitch (equivalent to the easy movement mentioned above).

So..is it the pump or the motor? The pump is Danfoss, the red body of the burner is'Ecoflam'.

Thanks in anticipation...