Those pumps fail pretty often so you are likely to be right. If there was a leak from the pump pulley area you probably will have solved it. The new pump will look slightly different unless it's been changed before. 2 clamps and 3 bolts and you'll know. They usually make a horrible racket as they fail.
The way that maytag tensioned that belt is odd but it works, the motor does indeed slide around and that motion is the tensioner.