Thanks guys,

I replaced that vacuum hose this summer with the white translucent stuff from the MB Dealership. It does not show signs of pink; also I did not see obvious signs of oil in the rubber 'U' that connects the vacuum hose to the intake when I shined a flashlight into it. However, on checking the trans fluid level, it is quite low. Maybe enough to have cleaned out the vacuum line.

While trying to find fitings to adapt one of my vacuum pumps to the modulator hose, AZ rented me a hand operated vacuum pump with the proper adapters.
Will test the modulator during daylight hours Sunday.