Hotpoint washing machine WM66p?

hi

Our 7 year old Hotpoint washer has begun to make a strange noise only when it spins. During wash is it quiet as a mouse but as soon as it picks up speed a sort of strange whirring noise like the noise of air going through a vacuum cleaner then it dissappears when the drum slows down to wash speed. I thought it sounded like the pump but much louder but when I switched the machine off during spin the noise was still there. I tried to move the drum to see if it was the bearings but there is no movement I have also looked in the back of the pulley and there is a hole with some grease coming out is this normal (not a lot but some running down the moudlings of the outer tub) if it is the drum bearings should I leave it untill the noise get louder or chould I change them now just in case?

thanks in advance