One of my valvues is making a horrible noise, how do I adjust?! on 2001 Audi TT Quattro

I just bought a 2001 audi tt quattro, an the previous owners had it taken to a mechanic to have the cover gaskets replaced. Apparently from the knocking noise, it is one of the valves. I cannot find anywhere on the internet on how to adjust the valve. I have had BMW's so I am new to working on the engine of an audi. Any help? Thanks.

Asked by for the 2001 Audi TT Quattro
1 answer 1 comment
not adjustable. you need to remove the covers and inspect for damage

I am pretty sure it is a clyinder valve. If not adjustable, how do I fix?