'92 2.5 Turbo: Replacing Vacuum Valve on Injector Pump

[srbays]

Dear MB Shop Colleagues,

The diaphram in the vacuum valve which shuts off the engine has failed and I need to replace the valve but I'm stuck. There are two torx-head machine screws holding the retainer ring but the back screw is inaccessible without removing the electrical connector behind the vacuum valve and probably the other square vacuum fitting to the right side of the vac valve. My 124 MB CD is mute on this topic and I've been unable to locate a Haynes manual or a 124 Bible locally (they'll arrive in two weeks from Amazon.)

I'm attempting to do this without removing the intake manifold because of the potential to introduce sand and dirt to this very clean/tight engine, but the manifold makes removing these two components tough. The electrical connector has a twist collar below it that has to rotate to release the connnector but it doesn't turn and I don't want to break it. With that out of the way I might be able to get two wrenches onto the square vacuum fitting on the right and take it loose too. The vacuum valve machine screw will be accessible at that point.

Could someone with experience tell me the following?
Is removing the manifold essential?
If not, how does the electrical coupling release? Does the collar turn clockwise or counter?
Did you need a holding wrench on that square vacuum fitting on the right?

Thanks.