Given a 6-10 window for the furnace guy to come and service the furnace, and possibly discover why it screeches, I was naturally pleased when he turned up just after 6. (Missed his "I'm coming" call, in fact, because I was having b'day drinks next door and left a scant minute before he arrived.) Was also pleased, sort of, that the furnace did not screech for him when he turned it on. He hazarded a guess as to what might cause the phenomenon, but the parts he named all turned out happy and sound. So furnace is clean and in healthy early middle age... and I hope it won't scream any more.
But of course I'm *very* pleased that it's not the motor or something needing replacement ASAP.