I used the capture mode on my scope to analyze that ringing more closely and it's definitely around 180 kHz.
Here's a schematic of a later production run showing the damper filter and unknown inductor L406.
That mystery value might be revealed in Riders Vol #13, but those pages are missing from my copy
Knowing that it's a 0.0068uF cap and 180kHz I pulled them into a resonance formula and got about 115uH. I rounded up to the next standard value - 120uH and ordered a few.
I hope it does the trick.
