The forward band is only applied in 2nd gear. The low reverse band is applied for braking in manual low and for reverse. The forward clutch is aplied in 3rd & reverse. My bet is all of these components are at least some what functional. How ever the direct clutch is applied only in all 3 forward gears. I believe it is failed causing your problem. I wouldn't mess around,just pull it and repair it. These transmisions are very simple to repair. Get a good book or find some one local to help. Not very costly either. Most of my stock Torque flite rebuilds cost less than $100 in parts.
Doug