I just changed out a faucet for a claw-foot tub. Simple enough but the new set came with plastic faucet handles. The cust wants to reuse the old ones, which amazingly, fit. However, the cold-water handle is bonded so tight to the cartridge I can't get it off. I tried heating it, WD-40 and a puller. I also tried hammerring the cartridge out from under the handle. Is there some sort of solution I can use which would ease the bond without destroying the chrome finish or the white metal?
Calcium deposits are usually the culprit on faucet handles. You may want to try soaking it with vinegar. CLR may also be an option but I don't know what the warning label states as far as being corrosive.
If you have never made a mistake, you haven't done much.
To remove handles from old stems without damaging the handle, cut the stem off and drill most of the remaining portion of the stem out of the handle.
You can use successively larger drills until you get to the point where you are left with just a thin wall of the stem and all of the handle. Take a sharp awl or punch and tap the metal into the hole you just created and peel the remaining metal of the old stem out.