How hard is it to change the draw mods on a patriot dually 03 and can i do it without a problem

If you can work a set of allen wrenches you're fine.

The mods are held in place with 2 screws per cam, all are accessible without pressing the bow.
Spin em' out, change the mods, spin em' in.
One tip......a little loc-tite. You should always use a little on modular cam bows where you could throw a screw.

You could probably change them faster than I could type this reply.

I second that! Almost had one pop off at a shoot that would have ruined my day so don't forget this step.

Fritz