TDI “ears” wanted

Hello together, something in/on (ne, rather in) my engine is tackert… It makes me crazy! ADAC said “Ventil beats on the piston floor” , workshop (older Audi man) says “ignore” my ears say “it doesn’t belong there, what is that” I know, remote diagnosis is always a kind of glass ball reading, but maybe someone is familiar with the tacker? Maybe I also hear ghosts? It comes more from the left (if I stand in front of it, so passenger side), while filming fell m I want to make it clearer in the back too… Thank you and greetingsMotor tackers