Will not pierce pod completely - Krups Dolce Gusto KP 2100 Espresso Machine

sounds like the wrong pods, or a part missing.

Google

make model pods falling through

I would pierce it Myself. It's worth a shot!

there are a few things that can cause this;
1) You may need to clean the needle in the coffee exit where the coffee pod sits and gets pierced when the top is closed. You do this with a needle, be careful the point of the piercing nozzle is sharp and the needle point is as well.
2) There is also a needle in the cup holder under the pod that cuts the hole for the coffee stream, this needs to be cleaned with the needle.
3) The filter in the water tank may be plugged and needs to be cleaned.
4) The pump may be clogged with lime and scale.
5) The heater element may be scaled with lime.
6) Items #3 to 5), to fix this use DE-scalier, or vinegar solution, the pickling strength works better than household variety, but both are OK.
7) run the cycle for coffee, no pod, 3 times, this should clear the taste of the vinegar.

Hope this is your solution.

sow, you need first do descaling second you need to to clean outlet spout just in case it blocked after this if coffee still does not come out you need to consider changing diffuser normally when you have a faulty diffuser normally the coffee goes in the waist bin at liest most of it

Some coffee machines have the option to either use ground coffee and filters or coffee pods. These are small, sealed containers that have the ground coffee inside. You insert the pods into the machine and click them into place. The machine pierces a hole and the water drips through. It's a much tidier way to make coffee especially if you don't drink a lot of it, so you don't want a whole jug full, rather just one cup at a time.

The capsules are not pierced when they are inserted. They are pierced on the back but not in the foil. The foil is pierced when the hot water is injected through the posterior holes and the pressure causes the foil to bulge, thus getting pierced by the grid in the front of the machine. If the capsules are not getting pierced it means that the water is not being injected with enough pressure. This could be due to hard water deposits. Try first to pump the machine by turning it on and then lifting the lever and keeping it raised for a few seconds. If that doesn't work, de-scaling the machine should correct the problem.

fill the water tank, plug it in, turn it on
open by handle in front, put in a pod, be careful NOT to touch the top there is a NEEDLE to pierce the pod, close it, put your cup under the spout, select cup size and wait. Just takes a minute.
You can also purchase a "my cup" which is a empty gray pod section that replaces the one with the needle and you can then use your own grounds making it cheaper to use.

try a new pod,,,first if this is the fault your home and dry

You may have gotten a unit that is minus the piercing apparatus. The little plastic piece with the piercer may come off with the used pod. This never happened to us but my daughter-in-law did, and apparently threw the piercer out with a used pod. They were able to order the part which seems to be easily removable - actually they ordered two while they were at it. Their coffee maker is working just fine.