Another '97 Escort Question...

Okay, so I've replaced the power steering pump in our '97 Escort, and now the belt is as tight as it possibly can be, and yet when you go and turn the wheel, the belt slips off the pulley on the pump, causing extremely difficult steering. Is there any way that I could possibly adjust the tensioner that is located right beside the pump so that it pushes the belt further against the pump pulley? If not, is there anything else I can do to fix this problem? Any info and help would be greatly appreciated.