I overhauled one of these recently after doing 100 miles out on Cape Cod and MVI. It sounded like it had sand in it and probably did so off it came. It was not much different than other FWs I've done and it was nice that SunTour marked the lock ring CCW to remove (vs CW for most other left hand threaded lock rings).

As to the 100 or so 1/8 ball bearings, that's never really been a problem. The old grease, no matter how bad, usually holds the balls in place until you open the unit and grab them. I always work in a shallow tray (old chinese food container or even the container for a dozen eggs) so those that 'jump out' are contained. If you're worried the FW has NO old lube then drool some motor oil into the back end the day before and that should be enough to ****** the ball's desire to escape from you.

"Assembly is the reverse of disassembly" using fresh grease and dental floss. Final tightening of the upper race and lock ring was a bit touchy NW but much like a hub bearing. Tightening the lock ring changes the fit of the upper race. Iterate it a bit and you'll dial it in. I did find one handy tip. The two notches on the lock ring were shallow and hard to grip. I had a segment of piston ring from an old engine (about 3" OD piston) which was high carbon steel and it arched over the center of the FW to engage those two notches nicely. I could screw the ring off and on with that then tap-tap-tap with a punch for final tightening.

One other idea: On my 6 FW bikes, I find a time each winter to remove the FWs and relube the hub threads. This ensures that they never stay on too long and get hard to remove. That ensures that I don't damage the FW notches with the remover tool - damage from having to apply TOO much force on the 'steering wheel' to get them loose.