Throttle body adjustment screws

[BJ]

Ok so I have built myself a 4 hose manometer and have had a look at the vacuum on the cylinders. My levels we're all over the place. I have discovered that the adjustment screws are soft soft soft even though they require very minor movement. These are the adjustment screws to balance 1 to 2 and 3 to 4. Even applying enough pressure to turn them causes the linkages to move and the manometer to go haywire. I was wondering if anyone has replaced them with stainless hex heads as I'm hoping it would make it easier to turn and adjust without necessarily having to exert pressure on the linkages while engaging the Phillips screwdriver.
I'm not game enough at this stage to just back them out and look for a replacement as there looks to be springs etc there. Would be great if anyone could supply a blow up diagram of that area or advise accordingly. Thanks

[Blubber]

On a different note:

A small restrictor or a needle valve is recommended in the feed line. This to dampen the movement of the gauges. 

[KiwiCol]

I'm with Blubber on this, if your readings are all over the place, I'd suggest you look at your home made meter rather than the bike.  If they were 'all over the place' in actual fact, the bike would run rough.  Is it?

[mlivkovich]

4 glass jars (really needed only 2), aquarium hose and some silicone done perfect job for me!

[Andre]

Maybe a different screwdriver will help. Try the one that came with the bike. I believe these screws can also take slotted drivers. I use a socket (Phillips) with a very short extension. Gives me the best feel.

[Hooli]

Tweak it, remove the screwdriver, blip the throttle & it'll settle to the new position to check your gauges.