The modulator is adjustable so figure it out before you get a new one or you could be back where you started. The proper way to adjust it is with a fluid pressure gauge. For now turn it a notch or two CW and see if shift crispness improves. Heck, you probably won't make things worse turning it a full turn or two. Keep track of where you started.

Sixto
83 300SD
98 E320 wagon