Bathtub faucet stem seat is frozen and won't turn.

Husky

It takes a hex head. I bought the appropriate tool to remove it but when I tried to remove it, the seat wouldn't turn. I prepped by spraying with WD 40 and waited 30 minutes.
We have very hard water and the seat must've been in there for over 20 years. There is evidence of corrosion and/or mineral build up. I want to try all the DIY solutions before I call a plumber, which I can ill afford, today.

Any suggestions?

TIA

Mike P

4just1don

First off WD-40 is worthless as a penetrate. get some PB blaster or Kroil,,they are MUCH better!!! Take something larger than the hex,smaller than the threads and tap a bit on them,,,hard enough to rattle the threads,not hard enough to force them thru the threads. Some of those are stuck so tight you HAVE to buy a new faucet. Try putting a longer cheater wrench on end of allen wrench for a little more leverage,,,but not so much you break whole faucet from its moorings!! Then tap on that,,,sometimes it takes a little vibration to kick things loose.