Hi Glen,
I had the same problem with my 333. I don't think the tach drives from Steiner's are long enough so I had one made up. There is a flat on the end of the tach drive that goes into the back of the generator. It just pushes in if I remember correctly. Inside the box on the back of the generator are two gears but you don't have to take this off to fit the drive.
I live in the UK so the company who made the tach drive up for me won't be much use to you I guess but you must have companies in the States who can do this.
Hope you get it fixed ok.
Alan