I still say that gearbox sounds like chalk across a blackboard. Isn't there
anyway to open it up and stuff it with a good gear grease? It must have
bolts on it somewhere. Is there a port to add gear oil?
Yes there's ways to open it up. The box sounds exactly the same way it did 12 years ago when I got it brand new. When I'm riding all I hear is the wind coming at me. This video is 9 years old.
Several in the past have opened these sealed Staton gearboxes up, thinking regreasing them would quite them down. Ultimately, most had to send them back to Staton to be resealed. The noise level remained the same.
If you need something that can handle the load of taking you up 30% grade hills these gearboxes are the best for doing that. My lowest gear has a reduction of 66.79:1. Some of the hills I've encountered I've never seen a pedal only bicycle going up them unless they were being pushed. I've also seen small cc mopeds not able to go up them either. Yet, I can go 8 mph up them.
That came with the Staton Inc rear rack mount kit. Now the Sidewinder didn't have dropout bosses like the LandRider did. So I had to weld steel flat bar on to the drop outs and seat stays to attach the rack brackets too.