Transmission slipping on first gear

[sakpase]

Hey! My 95 Benz s320 is driving me crazy i felt like getting rid of this car but i put too much money in it and i got no choice to fix it now, because i would loose more to junk this car now. My transmission is slipping on first gear only. All the rest of the gears are fine i took it to AAMCO and they told me that i have an internal problem in the transmission and they quoted me $1600 to rebuild it. When the car is on drive and i press the gas slow it takes a little while and go to second gear. If i press the gas like i should when the car is on drive i could hear the car reving up and hardly moving. Beside first gear i have no other problem i drove the car in the high way doing like 80 mph without a problem but when i come to a complete stop and started moving again it slipped on first gear then fine on all the rest of the gears i was wondering if it's something that i can probably fix on my own. A benz tech thought it was the valve boddy and he checked it and told me it's not the valve boddy it's the first gear in the trans. Thanks