Sounds like your sun gear is not meshing with both the planetary gears or the fixed cog made onto the axel? When the cable is at rest (no tension), The sun gear should move outward from the center of the hub toward the sprocket side and eagage the fixed cog and that gives you low gear. When tension is placed on the cable, the sun gear should move toward the center of the hub and engage the planetary gears and this gives you high gear. Sorry, I don't have a hub that is apart to show you. But try this before you do anything else. Loosen all the lock nuts on the axel where you can thread the axel inside all the guts. On the brake arm end of the axel, there is a screwdriver slot. Get a flat screwdriver and if I remember right, turn the axel counterclockwise until it bottoms out then back it off about an eighth of a turn, If that don't work try turning clockwise? Once you get it where it will shift, adjust all the slop out of the bearings and tighten the lock nuts on the axel.
if you get the sun gear properly seated in the fixed cog, the shifter and index should mover the sun gear enough to engage both the fixed cog and the planetary. Hope that helps! And I may have all of this backwards, but thats how it works. Thanks!!!
