Hello,
I have recently modded my Cimbali Junior D/1 with a dual-scale manometer gauge, to show both boiler pressure, and pressure at the brew head (or at least after the vibe pump).

I am taking my brew-pressure reading off of an extra nipple present on my overpressure valve (OPV), which was previously capped. I've drawn a diagram of my configuration.

Issue is, when I brew, I do not currently get ANY reading on my brew pressure scale. Could the issue be that there is air in the brew-pressure-pipe back to the gauge, that I need to bleed?
I suppose the brew pressure scale of the gauge itself could be broken? (but the tank pressure scale works fine).

Thanks!

The small copper tub to the lower gauge might be kinked, or the lower outlet from the tee fitting may be blocked by the spring loaded valve. Have you checked to make sure the lower tee outlet is open and under pressure when the pump is running?

Air wouldn't hurt it, the air in the capillary helps to steady the needle.

If you take back off from the OPV, does it drop to zero? It sure looks like it's reading some very small pressure in the photo.
If you run the pump with the brew valve closed, or the blind basket in, does it move at all?

I tried bleeding the air out of the capillary line, by disconnecting it from the gauge and running the brew pump momentarily until water dripped out the capillary.
I then re-connected the capillary pipe to the gauge and now DO see a brew pressure reading when I brew against a blind portafiler (brewing and letting water just pour out the brew head shows no pressure, naturally).
Still doing some experimenting, but I think the air in the capillary line was my problem.

Pressino wrote:The small copper tub to the lower gauge might be kinked, or the lower outlet from the tee fitting may be blocked by the spring loaded valve. Have you checked to make sure the lower tee outlet is open and under pressure when the pump is running?

The tube does not appear to be kinked.
The spring valve does not block any of the lower inlets/outlets (I inspected them all when I had the piece off for cleaning at another point).
The lower tee outlet IS under pressure when I brew; water will pour out if it is left open/uncapped.

OK, then it's possible that the lower gauge is not sensitive enough or may just not be working properly to register the pressure you are sending it. When your machine is pumping against a blind PF the gauge should read whatever pressure the pump is set to...usually somewhere between 8 to 12 bar.