I had one of these and it did this for months, I was constantly adjusting. Finally I brought it to the shop where I bought the wheel, and they couldn't get it right either. They replaced the hub internals under warranty. Shortly after that, I sold the bike. Fast forward almost a year--I ran into the guy I sold it to, and told me he had to have the hub internals replaced again. From my experience, these SA 5 speed hubs are really unreliable.
1964 JRJ (Bob Jackson), 1973 Wes Mason, 1974 Raleigh Gran Sport, 1986 Schwinn High Sierra, 2000ish Colian (Colin Laing), 2011 Dick Chafe, 2013 Velo Orange Pass Hunter