Nutronics D509V2 spinning 300RPM on low density mode

[SomeGuy]

I have a Nutronics D509V2 1.2mb 5.25" drive here - the way it is jumpered it looks like it should spin at 360RPM in both density modes, but it appears to be flipping to 300RPM despite the jumper setting.

I don't see any detailed information for this model out there off hand.

Jumpers are:

DS1 [O-O .] DS0
DS3 [. . .] DS2
HD  [O-O .] LD
MS  [. O-O] MM
RDY [. O-O] DCH
2S  [. O-O] HS

Now, I'm guessing that 2S means "2 speed" and "HS" means high speed. So flipping this jumper should give me the behavior I am seeing, but for some reason it is switching speeds anyway.

If I change the jumper, it does nothing different.

I did try changing the HD/LD jumper, and that inverts the density signal, but still uses 300RPM in the low density mode.

For sanity, tried different jumpers. No difference.

Does anyone have any more information about the jumpers on this drive model?

 

[Chuck(G)]

There was a discussion about the Mitsumi/Newtronics drive here about 7 years ago: https://forum.vcfed.org/index.php?threads/floppy-drive-jumper-settings.56473/post-56473
Also see: http://www.verycomputer.com/74_932f9b5979e89b95_1.htm