Bring it to transmission place, I am sure they rather get paid to rebuild the entire transmission compared to fixing what is broke. Good time to add a shift kit for 50-60 more. The shorter shift time allows the friction elements and gears far less time to wear themselves out. The useful life of the friction elements in a transmission is directly related to the amount of slipping that is allowed to occur during shifts.
Slipping converts useful energy to heat on the surface of the clutches and bands. This heat transforms the friction material to ash, which polishes its mating element, causing further slipping, heat and deterioration of the friction elements.
The gears receive less wear, too. A slow shift causes them to be partially engaged for a longer period during the gear changing process, resulting in unnecessary heat, wear and power loss.