Cleaned our Giotto and the pressure gauge reads .4 bar when machine is off and cold.

Pulled the gauge out and currently have stem soaking in descale bath.

Not sure if this will work.

Any other suggestions on getting the gauge back to normal.

This machine is 10+ yrs old but we'll taken care of. Believe it is V1 with single gauge.

After descale bath and suction the needle still rests at .4 bar.

I was able to use a silicone straw to suck and draw the needle back to 0, but it bounces back when to .4 at rest.

Hooked it back up and turned on the machine.

Needle reads around 1.3 bar (normal) and moves as expected as steam is used or boiler calls for fresh water.

Machine is cooling off but appears to be back at .4 bar.

You can leave it as it is and consider its new location to be the "normal".

If you want to risk damaging it, you can take the face and glass off of the gauge (the front shell is just pressed onto the back shell), pluck the needle off of its axis, press the needle back onto its axis at "zero peg", then press the front shell back on over the glass.

Or replace the gauge and keep that as back-up.

Had the same issue on a machine, I ended up just replacing the gauge myself.

Appreciate replies. We'll see how long I can fight off my OCD to replace it!

Pulled some tasty shots and steamed up some nice micro foam this morning.

Hi Van G.

Which model of Rocket Giotto is this and what was used to clean the machine?

With the machine at full pressure and the gauge reading its normal high maximum pressure:

1. Shut the machine off;
2. Open the steam wand and vent the excess steam pressure in the Steam Boiler;
3. As the resistance in the Steam Hydraulic Pathway drops, tap the pressure gauge. This may need to be done a few times looking for any possible changes in return to the zero setting.

If this doesn't work, there could be some debris that has come lose and is in the bourdon tube or the capillary tubing (the thin copper pipe that runs from the boiler to the pressure gauge). If there is a clog of some type, this could require some further descaling and patience to verify the capillary tube is free of obstruction and the bourdon tube is clear of any debris or other air/fluid bubbling etc. Take care when handling the capillary tube as it is quite thin/delicate piping.

Clogging and Non-Zeroing in Bourdon Pressure Gauges
There are several reason why a Bourdon Tube version pressure gauge could develop a fault or fail completely.

1. Undamped Rapid Pressure Fluctuations can result in damage to the gear teeth and other moving components of a bourdon pressure gauge. Tube fracture and stretching of the tube can also develop over time with rapid pressure fluctuations that are not dampened. As well, loosing of the internal components can develop where they attach and slide at junctions including tiny screws, and slotted guide pins. In critical situations where pressure measurement cannot be incorrect, a Pressure Snubber can be inserted in the pathway being measured, however, this is impractical in espresso machines as Pressure Snubbers usually need to be at least a meter/3 or 4 feet from the pressure gauge in the connected piping. Pressure Snubbers can be placed right next to a pressure gauge but they need to be carefully designed and correctly calibrated;
2. Pressure Ripples are very similar to the problems of Undamped Rapid Pressure Fluctuations but originate is in a centripetal pump (like a vane pump) or relief valve when high-frequency impulses impart a rapid stuttering in the hydraulic pathway causing damage to a gauges internal components (gear teeth etc.);
3. Vibration to the gauge through the Machine's Chassis/Case or gauge's Receiver Block (the brass block fitting the gauge is attached to). Vibration can cause excessive forces on the gauge's internal components. Bourdon Tubes have a periodic nature that can communicate vibrational forces (for example to gear teeth, pivot pins, connecting link etc.). Generally speaking, this is not an issue in espresso machines;
4. Stretching of the Bourdon Tube any duration of excessive pressure that exceeds the designed specification of the gauge. Again, the gauges for espresso machines generally do not suffer from this issue (other than through an extraordinary anomalous spike in pressure or drop in pressure) as the gauges are selected to cover the possible ranges in both the Brew (16 Bar gauge maximum usually) and Steam (3 to 4 Bar maximum usually) Hydraulic Pathways;
5. Sudden Pressure Release for example when a component fails or during the diversions through piston manipulation inside a Solenoid. This may impart large forces to the gauges needle and internal components. Most espresso machines do not have a Check Nut to prevent these forces from abrupt impacts to the gauges internals. A Check Nut has a piston internally that does not interfere with resistance in the hydraulic pathway as resistance increases, however, if resistance suddenly drops in the hydraulic pathway, the piston valve seals and a conical opening that tapers from the gauge back to the machine's internals forms a slow leak orifice that releases the pressure back more slowly. In this way it is a bit like a one-way-check/non-return valve but it has a slow leak via a tapered hole through the sealing piston valve stem. I'm not sure if any espresso machines employ Check Nuts or if there is muc need for them unless the fast switching of a Solenoid or sudden drop-out resistance of a 3-way solenoid valve exhausting group/coffee puck excess fluid is resulting in such a sudden pressure/resistance Release;

Any clogging in the boudon tube inside the pressure gauge or in the capillary tube could result in inaccuracies. Here's a great little video primer by a brilliant youtube creator mrpete222 (Lyle Peterson), about pressure gauge internal components and function including of the bourdon tubes found inside these amazing espresso tools . . . All credit to: Pete at mrpete222 and Youtube