How to Avoid OverExtraction?

[JJHippo]

I have already bought a Gaggia Espresso Machine.

However, I found that the espresso seemed to be overExtract, because the espresso is made "drop by drop" .

I cleaned all the staff and sured that the hole was not blocked.

So, how to avoid overextraction?

 

[LiftOff]

Grind coarser and tamp using less pressure.