it didn't happen because i hadn't changed the needle. it happened because i was sewing over pins. the dumb luck part of the story is that hitting the pin straightened the needle and knocked off whichever infinitesimal burr had made it dull and noisey.
i've had to dig pins out of my bobbin area many times before on many different machines over the years. nothing new about that. this is the first time it ever renewed a needle. usually breaks them. i'm also fascinated by the quieter run and better tension. those two must be my imagination. i guess. who knows. :lol: