95 S500

I had the transmission rebuilt because the reverse clutches were out. When I got the car back, it felt like it was sticking or even slipping between 3rd and drive. The shop told me to adjust the modulator. The problem is better, but now the shift from 2nd to 3rd is hard. Could this be a bad modulator? Is it possible that a valve inside the tranny could stick?

Thanks,
Lyndon