Is the old flange still broken?

Did the toilet work fine until the flange broke?

Are the mounting screws properly contained in the flange?

Is the floor level(even) where the toilet sits?

If the flange is still broken, it must be replaced. Replacing the flange will take care of the mounting bolt problem.

If the floor is unlevel(uneven), there are shims(I recommend the plastic ones) sold at home improvement/hardware/plumbing stores to install to stop the unlevelness.

The only other thingt of which I can think is that the old wax ring/funnel assembly was not removed, causing the tiolet base to sit too high on the new(succeeding) wax rings and cause the rocking.

There is an alternative to the wax ring you might want to try as well. A friend of mine that manages apartments told me they work great. See the LINK below:

Here is a link that might be useful: Wax Free Gasket

Mac is right -- the flange must be replaced and the floor flat. Shim the toilet so it doesn't rock if necessary.

I've used the "wax free" devices that Drywall Guy suggested. They do work but the basics need to be right as well.

One word "plumber"

I ment to add if all else fails