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Low shot weight


The 9Barista produces a shot of espresso which should weigh between 35-40g. If it’s lower than this, there may be an issue which needs to be resolved. The suggestions below will help you diagnose what’s going on.



There are two possible solutions to this problem, as follows.


1. Leaking boiler o-ring

A low shot weight is usually an indication of a leaking boiler o-ring. This could be a result of either limescale build up, or some damage to the boiler o-ring itself. The first step is to inspect the o-ring for signs of damage, limescale or stretching. If in doubt, we’d recommend that you replace it. A spare is provided with all machines, but if you don’t have that you can buy replacements here.


If you live in a hard water area, or if there are signs of limescale on your machine, we recommend running one or two descaling cycles and making sure there’s no scale or debris in the groove in which the boiler o-ring sits. You can find instructions on how to do that here. If the problem persists after descaling we’d recommend replacing the o-ring.



To protect the boiler o-ring from future damage, be sure to lift / pull the pressure release tab on the safety valve (see below). This neutralises the pressure, making the boiler much easier to unscrew as well as preserving the longevity of the o-ring.


2. Leaking valve pin seal

A low shot weight can also occasionally be caused by a leak past the valve pin seal, although this is less common. If solution 1 didn’t resolve the problem, the next step is to run a descaling cycle. If that doesn’t help, you’ll need to disassemble the machine and inspect the valve pin. To do this, follow the disassembly instructions; at step 3 you’ll be able to access the valve pin. Give it a good clean and rinse to ensure there’s no scale or grit in and around the valve pin or the valve spring, or inside the valve chamber. 

If these solutions don’t help please contact us and we can provide further assistance.

Updated on 02 Aug 2023