You probably need to supply a little more info to get others to help you.
How does the coffee in the GC look after the extraction? Is it wet, dry, clumped or runny?
How old is the coffee? How long has it been in the freezer?
It seems you might be trying to put too much coffee in the basket. I also think it is crazy to draw any conclusions before you clean and descale the machine. This may never have been done before! Get some coffee cleaning solutions from one of the sponsors here and run it through the machine.
That is a start. The more tech stuff I will leave to those in the know!