automatic transmission malfunction

[pep]

My sl500 auto transmission has a peculiar shifting. The second gear takes longer to shift and it does it on and off, sometimes shift ing great and others taking longer to shift or hard shifting. I changed the trans fluid, but it hasn't improved its condition. The other gears work well. Need help, I don't want to replace the trans and don't want to go to a trans repair place without an idea of what's going. IT is a SL500 Roadster 1994 with 88000 miles.