EJ22 help needed ITT

Ok so the other day my car started making a ticking noise coming from the passenger side valve cover (assuming its a lifter) before I go dismantling anything are there any tricks (oil additives) that might work to fix this issue and are Subaru lifters adjustable or do they just need to be replaced? In the end I have to remove the valve covers anyway and replace the gaskets that have a slight leak but I’m just trying to avoid a bigger headache working on the lifters since the valve covers are in quite and inconvenient place to begin with on the Subaru.

Thanks in advance!