Here is what I have done (1994 940 Turbo wagon):

Checked the check-valve under the hood -- blowing into it, no air goes through from one side and air (somewhat restricted) does goes through from the other side.

Bought a mighty vac and checked the vacuum motors --- the usual culprit one holds a vacuum; the next closest one holds a vacuum in one line, but the blue line does not.

Checked the lines that leave the motors --- these do not hold a vacuum.

I do not see any vacuum tank -- do 940's have a tank?

The lines look like they go from the motors to the MCC. Do I next need to pull the MCC and check the lines and the pipes they plug into? Should the pipes into the MCC hold a vacuum?

Thanks,