But Does Anyone Call Me Jack the Plumber?

I have spent a large part of the last several days decisively demonstrating four or five things that were not the cause of low hot water pressure in the upstairs bathroom. And making myself quite frustrated and unhappy in the process. Inanimate objects are just hateful.

It isn't sand grains in the shower head because I checked. In any case the cold water comes out just fine. It isn't a defect at the valve because I took it out and changed the washer. It isn't even a clogged supply pipe. Turning on the water with the valve out did blast out half a handful of small gravel but since it blasted them out, they weren't enough to restrict the flow. It isn't a clog in the riser to the shower head because the cold water comes out enthusiastically. The obstruction seems like it must be between the hot water valve and the tub spout, in the mixer. Unfortunately there seems no way at all to get at it from the valve side.

New tenants arrived from Canada an hour ago so I will not be able to work on it any further until they leave a week hence. The only option I have left short of having a plumber open the ceramic-tiled wall to cut out the mixer, is to unscrew the tub spout with a strap wrench or a pipe wrench padded with paper or cloth so as not to damage the spout.

Possibly I can work something in through the spout nipple to attack the obstruction. Or even take the nipple out so as not to work around two corners, only one. Conceivably I could suck whatever it is out with a tube connected somehow to a vacuum cleaner.

In the meantime, the tenants will have no hot water pressure to speak of for taking showers upstairs.

The whole thing has become what lesbians in Oakland used to call an AFGO. Another Effing Growth Opportunity.