My 66 has these hard plastic vacuum lines running from the servo motor under the hood to various places. The one on the heater valve (red stripe) came off and won't go back on. Any advice on just how these inflexible plastic vacuum lines are supposed to be attached? You can't just flex them on like the rubber lines apparently and it just will not stay attached

I was thinking of replacing them with rubber but they are not coming off on the other end, so that kind of went out the window. I don't want to break any of the little plastic connectors they are attached to

 

They are attached in the pic to the rubber block on top of the large round servo motor

They also won't stay attached to the small round white thingy as well, keep popping off