vacuum modulator

i was wonder how could i tell if my vacuum modulator is goin bad cuz my c-6 is takin long to shift or sometimes takes a while to shift into 3rd, the trans fluid is good i checked that already and it seems to shift into 2nd fine, but itll takes forever to goto 3rd and also i tried adjusting the modulator valve and nothin happens, im suspecting that its bad cuz the car shifts the same no matter how i adjust it anyone know anything about this

It would be worth a shot changing it since it's not too expensive but don't know if that would be the problem or not. My modulator had a vacuum leak so had it disconnected for the test drive and it hesitated just a little bit from 1st to 2nd. This is a cruisomatic but think they all act similar. The tranny before this one wouldn't shift to 3rd for a long time and then one day the torque converter spun on the shaft or the tranny locked and caused it to spin, not sure which. It was toast. It would work ok until the tranny warmed up after that though, which didn't take long.

Deb