Finally got mine on Wednesday.... but it was worth the wait! Removed the two original focuser knobs on the NP101is and the HSM fitted straight on. I found that the little hex screw holding the 1:1 focuser knob is locked in by a second one, luckily I found that out before I used force....
Step size 1.3microns. Works like a treat, and integrates perfectly with SGP.
I would definitely recommend it as an elegant solution for automating focusing on Televue scopes....but pictures say more than words....
Cheers,
Christoph