I'll probably be out of order here, but on 78on the res was in the tubular steel section welded between the chassie rails at the front roughly under the lights, I could park, come back a week later, pull the switch and up they came (no engine running). Get some vaccumn & tube and put it straight onto each actuator. One of mine developed a hole in the actuator rubber diaphram so I replaced it as a complete unit. With Vac on each they should, if not siezed or Impeded, come straight up/down. Having said this, please remember, 71 is not forteau. On a VK Commodore upon heavy accel, all dash A/C outlets would go haywire, I used a black plastic cystern float ball (easter eggy shape) brass fitting each end plus one way valve - instant cheap vaccum reservior. I hope something here helps. Bfit would know better than I, but lumpy cams I believe, may also cause lose of vac.
