If you have an espresso grinder and it is no longer sending coffee through the chute it may be because the burr chamber is clogged up. This can happen if the burrs are set too fine for the grinder to be able to push the beans through and is more likely to happen if single dosing with an espresso grinder (we will get into how to avoid this below).
If this happens the burrs will get jammed up and the motor won't be able to push the burrs to spin because of the clogged up grind in the burr chamber. If that is the case you will likely hear the motor making a quiet hum and you won't hear the burrs spinning and grinding the beans. The resolution for this is usually setting the burrs to grind coarser. Sometimes if the grinder really jammed up you will need to remove the top burr of the grinder to get the built of beans out of the assembly but first we recommend loosening the burrs.
This can happen with any grinder from a grinder with a smaller motor like a Eureka Mignon all the way up to the powerful Macap M7D and Eureka Zenith. If the burr chamber is clogging up it is very rare to see an actual defect in craftsmanship(although it does happen) but rather we tend to see a mis-dosing of when it comes to the overall process of making an espresso - let us explain:
With the overall goal of pulling an espresso being that you want to have a certain amount of espresso produced in a certain time we can overlook how much ground coffee we are putting in our baskets and if we are putting enough coffee in our baskets. For instance below is a photo of a single, double and triple basket.
Each basket has an intended range for the amount of coffee that you want to put in the basket to pull an ideal espresso within an ideal timeline. The ideal is with a single basket roughly 7~ grams in, double basket 17~ grams in and triple basket 21~ grams in.
If too little coffee is put in a double basket, let's say 14 grams, then in order to follow a recipe for extraction, let's say 1:1.5 coffee in to coffee out in 28 seconds, you will have to tighten up the grinder much finer than you would need to if you have used closer to 17 grams in. This is because the water has to travel through less bean in order to pull the "1.5 out" part of the ratio.If the burrs are tightened up too close then any grinder will end up having jammed burrs because the exit path for the espresso grounds has been made so small that the particles cannot be shoved through the burrs.
So, most of the time the solution is to verify which size basket you are using and how much beans you are putting into the basket. If your ratio in is too low and you are trying to pull 28+ second shots it is entirely likely that the grinder needs to be dialed back a bit and more grounds introduced to the equation.