Check hot water heater (on). Check production of hot water at a sink tap (hot water was there). Disconnected hot water hose at washer (hot water was coming out of hose.) Google for possible causes (found water inlet valve was usual problem). Ordered new inlet valve from AppliancePartPro (new inlet show up a couple of days later.) Watched video on replacing inlet valve (looked pretty straight-forward).
Took about 15 minutes to replace valve. (Had to run back down to basement to get nut driver - I brought up a Philips-head screw driver first time around - wrong).
The hardest part (and not counted in my 15 minutes) was wrestling the dryer out of the way and getting the washer out of the overflow pan it was sitting in so I could move it from the wall - had to lift washer, push 2X4s under it to raise it above the lip of the pan, and then put more 2X4s outside the pan to slide the washer onto. (the pan was not movable, because of the drain pipe in its bottom that effectively fastened the pan to the floor). Then, after the valve replacement, I had to slide the washer back into the pan and remove the 2X4s from under it. This procedure was by far a bigger pain than making the actual repair.
Hot water is now getting into the washer as it should. :-)