i dismantled only the square part to clean the metal filter. A 1mm seal fell out of no where and wasnt sure where to put it back. I placed it back into that L shape piece on top of it and now there is some coffe leaking into the square piece. Please help. I have the diagram to show the exact piece i mentioned but how do i show it here?

I have a Saeco Royal SUP016R model. Just cleaned the brew unit and a 1cm rubber seal fell off and i have no idea where it came from. Now there is some leak on top of the brew unit and the coffee ratio is off. Can you please help?