Transmission 1991 125c no reverse

I just bought a 1991 APV with a 125c transmission. The transmission is slipping in reverse, it has 76,000 on it (knowingly bought it this way). The fluid was changed at 18,000 and 42,000 miles. I removed the pan and the fluid was blackish probably from the reverse clutches burning. The van goes fine foward. Waiting for your suggestions before I put the new fluid in. Does anyone know the problem, have any quick fixes of is it in need of a rebuild.

No quick fixes here, it has to come out.