The story has an ending!!!

 

Boy did I get a lot of responses and helpful suggestions.

 

The water filter problem turned out not to be crystalizing mineral salts jamming up the threads (as I most recently suspected).  Jazi suggested I go press the pressure release valve on the top of the filter.  Well, I didn’t need to do that because I had already released the pressure, but her note got me to thinking.  Brother Tom had already made a suggestion about releasing the pressure, but I wasn’t ready to revisit the pressure release yet then.

 

I started out thinking that I could go press the pressure release button just to prove that the pressure had been released.  (No way the filter canister is going to unscrew if it is still under pressure.)  I knew there was no pressure because I had closed valves on either side of the filter and released any pressure by turning on the kitchen faucet.  Problem is, the filter is between the two valves, but the kitchen faucet is not, so the pressure I released from the faucet was not the pressure I needed to release.

 

So I went back out to the filter, looked for the pressure release button, couldn’t find it, then followed brother Tom’s suggestion and only closed the inlet valve to the filter, didn’t close the outlet valve from the filter, and let the pressure out with the kitchen faucet.  Pressure off, barely needed the wrench, filter removed and replaced.  Piece of cake!

 

Again, thank you all.  Put this together with yesterday’s report and we have a complete story!