Hi and welcome to Just answer.
Initially, high pitched sound or noise is usually cause of clog air on the water line and pump system. My first suggestion is try to descale your machine using recommended saeco descaler.
If still, try to manually prime your machine, for instruction CLICK HERE it supports all gaggia and seaco models.
Sometimes you need to get rough on your machine in able to remove the clog air on water line. slamming the water tank into machine sometimes help. If still, unplug your machine, remove water and turn the machine upside down or shake your machine if possible.
Let me know if you still have questions.
Note: Please do not give negative rating,that is not helpful on both of us it just destroy my overall performance. Just reply if still persist.
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I'm just following up with you to see how everything is going. Did my answer help?
Let me know,Chester