Gasket here?

[LordGrover]

Being a bit of a mechanical incompetent, would someone please advise whether this is a broken gasket or just a poor seal that a bit of grunt on a spanner will resolve?

[Talkwrench]

That is definitely a tired gasket.
You'll shear the bolts and still never nick that up tight enough to seak it for any length of time.

[Barreti]

Mine has the 8 bolt flange but if its anything to go by you could undo the bolts and slide a new gasket in.
Worth having a go.