Just picked up a 2503 1/2” drill. How hard is it to swap the chuck?
It's stupid easy. Just know the retaining screw is LH thread. I prefer to use an impact driver in forward, much less chance of boogering the Phillips head.
Then clamp down on a hex key, put the right angle of the hex key between vise jaws, put drill in reverse and let 'er rip. If stubborn don't clamp the hex key tight; allow a gap on the jaws so the hex key can "slam" into a jaw, effectively allowing an "impact" effect.
There's a million other ways to do it (some prefer hammering the hex key on a bench).
For EXTREMELY stubborn ones I've put a hex socket on an impact wrench, chucked up on that, run the drill in reverse and the impact the other way; don't do it for long or you *could* burn the drill up but it shouldn't take more than a couple impacts.