Thanks all.
I don't know what shape stylus is on my clearaudio maestro v1. I think they use their own shape. The stylus tip looks much smaller than what I used when I was a kid.
All I could find relating to the tip shape of Clearaudio carts was this old article from Issue 1 of positivefeedbackonline.com:
"The family of moving magnet cartridges from ClearAudio includes the Alpha, the Beta ($350), the Beta-S ($450) and culminates with the Virtuoso Mk II ($850). It is an unusual specimen to my way of thinking as, like all of its lesser and greater siblings, it has a stylus profile of 4 by 40 micrometers. I’m used to the better-known and more pronounced elliptical shapes of the Shibata, line-contact, fine-line, van den Hul, and hyper-elliptical designs. Most of those stylus shapes have profiles of something like 3 or 4 by 65 to 80 micrometers. A little searching revealed that that Clearaudio’s stylus shape dates back to a late-1960s Japanese design purchased by Peter Suchy, Robert’s father, and still championed to this day."
Peter Suchy is the founder of Clearaudio, so it's maybe their proprietary stylus shape. I don't know whether my newer cart model still uses this shape, but if so, it implies that the tip is even narrower and able to ride even lower in the groove than Shibata. Could it be that I'm riding too low in the groove and hitting gunk driven down into the gutter?