access chamber sealing gasket

[<me9]

I've an access chamber with a screwed down lid, with a sealing gasket to prevent contents/smells leaking out.

During a recent blockage it was leaking. It seems to be a soft black foam strip similar to draughtproofing strip, about 12mmx5mm glued in with what looks to be Evo Stick. It's been there about 15 years, and has perished.

What is the best material to replace this seal? I'm contemplating filling the groove with silicone clear sealer, levelling it off, and letting it cure, then fitting and screwing it down.

What does the assembled expertise consider to be the best method of sealing this cover?

[Frank Erskine]

Insertion rubber is your friend.

[<me9]

Is that a technical GPO term for LRC's finest, as kept in the first aid cabinet for emergency use only?

[Frank Erskine]

It's gasket material, as used for steam pipes and fittings...