I was not able to understand your test proceedure.
However, on my year and model the Vacuum Valve that goes on the Ignition/Steering wheel lock is a $25-$28 item + shipping. Some places will give your free shipping for $50 or more.
At the point you haver reached if it was me I would just buy a new Valve and some other items I need like filters, extra fuel return hose, extra Glow Plugs and so on to get the free shipping.

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84 300D, 82 Volvo 244Gl Diesel