A couple of questions -- since it just started, I'm wondering where the air could have come from? I've tried running the water in all the faucets high and low to try and bleed it but don't see much difference.
I've read that it could be on the downstream or upstream side of the valve - do you know any way to tell? Sounds like there are different things to try and I'd just as soon start with the most likely and easiest ones first.
Some more info (pull up a chair, boys, LOL!!)... the toilet, sink & tub all tee into the same line within a couple of feet of each other, but only the toilet hammers. Also, in the other end of the house - about 30 feet downstream of the toilet, the kitchen sink faucet hammers.
Welp, that's my story. Any help or good guess much appreciated.