Help Needed!! Disco 300tdi

Hi There
after fitting a new water pump, me and my father in law noticed that when putting the drive belt on that the pulleys didnt seem to be in line and when the engine cranked up the belt was slipping to the left side of the lower pulleys, after lookin at it, it looks like the power steering pump shaft has moved out slightly thus stopping the pulleys lining up, tried leavering it back in but there was no movement at all, just wondered if anyone had any ideas or advice.
many thanks

some of the pulleys can be put on wrong way round ,failing that another pump

cheers its just the pas pully that doesnt seem to line up so will check that its on the right way, cant be the others as I havent had them off only the water pump pulley and lines up with the rest, so will check and maybe new pump then.
Thanks