1994 Plymouth Acclaim Shifting Problem

My '94 acclaim won't shift out of 1st gear. I had the transmission filter and fluid changed at a dealer, which I thought cleared up the problem. It's been 3 weeks and we are back to shifting problems. It has a tendency for hard down shift and use to have a delay in shifting when slowing down, then speeding back up again quickly. Consumer's Guides say the 41TE transmission had problems with bad seals. What is your take on this condition as probable causes?

Thanks,