I finally got sufficiently annoyed by my bench grinder's violent vibrations. I took off the discs and discovered that the little discless stubs are already wiggling themselves quite substantially. First problem to solve is (probably?) to make the arbor straight.
However it seems like a pretty solid piece of steel. Do you have any experience with straightening such a machine part?
The first thing that comes to my mind is to grip the arbor in a vise and either slam it with a rubber-wrapped hammer or stick a pipe over one end to just the right depth and push on it. Taking an unbiased look at my machinery repair record, this is likely to make things worse. Since I will probably need to balance the discs eventually, would it make sense to let the arbor as it is and compensate by balancing the discs in a slightly crooked way?