Simonelli Prontobar Strange Noise

Hi All,

I inherited a Prontobar and have fallen in love with it. I haven't completely stripped it yet, but I've taken apart most of the components located at the front of the machine for cleaning and replacement where necessary. I've also spent weeks perfecting the settings. I wouldn't say it is perfect, but I will say it is now making amazing espresso.

I have one issues remaining:

When the piston moves up and down the machine makes a loud 'rubbing' noise like a part is rattling or not lubricated properly. I am worried that I am unnecessarily wearing out parts every time I use the machine, and that the issue may be related to the Group Setting above. I've ordered a bunch of spare O-rings and will be taking the piston and gear assembly apart to clean and lubricate it but I am wondering if any technician is aware of what the issue might be.

TIA!

AB