700r4 not shifting into overdrive on 1990 Chevrolet S10 Blazer

actually an 89 but that was to old for the selection list but anyway i just changed the front seal due to a fluid leak all went as well as that could but now it doesn't shift into overdrive with any regularity please offer any advise that may help thank you

Asked by for the 1990 Chevrolet S10 Blazer