Cheryl called the rental-management company, but it was nearly 5 PM and the repair company to which they transferred us put her into voice-mail. After slogging my way home through awful traffic, I examined the situation. Fortunately, I was able to get the tap closed. In an echo of Flanders & Swann, a past paint job (not the one from yesterday) had dripped onto the tap, making it very difficult to turn. I would have got a wrench from the tools in my van if necessary. Now the hot water in the washer is turned off, ending the threat of flooding (not to mention the waste of water and energy).
The earliest we can expect any action on this is tomorrow, I guess.