easy diagnosis

O.K., so I know how easy it is to diagnose a transmission over the net, but I'll ask anyway. '94 exploder with the v-6 two wheel drive. The transmission started slipping, or flaring when it goes into second. If you let off it will sometimes make the shift and move on through the gears. The car is parked now. Any guesses? Worth rebuilding or call the junk man? The car is in average condition with 100k miles.
I'm outa town for a few days. Gotta go to the Remington armorer class for my four year refresher.