I remember a story about a person that suffered very much and went to see a certain rebbe to help him. While waiting he feel asleep and had a dream where he saw his mitzvos and aveiros and the avairos fair outweighed the mitzvos - but then the angels brought in more trucks and starting unloading bags onto the side of merit. He asked one of the angels what are these and the angel said this is the suffering that you went through. As they unloaded the bags the scale started to raise the side of merit and as the emptied out the last of the bags from the truck the scale was exactly even. He woke up screaming "more suffering!! I need more suffering"
That's basically the story. Does anyone know the source?