14-16 inch ventilator with oscilation.

the Ventilator oscillate orbitaly, having the same horisontal and vertical axis, but the engine rotates slowly to send air all around, the problem is this: the blades do not want to rotate after a day or even 2 hours after shutting down. The blade can rotate from a magnetic force which allow the shaft (which the blade is attached on) to rotate. As it was brand new, there was no problem, but now it almost seems as it jams and sometime require a bit or manual force to help it start it's rotation. What im asking is this: What can i do to make it work properly again. I have some solutions but do not know which would be wise. Should i dismantle it completely, grease movable parts that requires it and remove all traces of dust or do something else? hope everything was detailed properly...