Leaking pastic soil pipe stack cover

[londondiy]

Installed when the house was built in the 70's.
Does anyone know where can I get a replacement cover ? (or gasket) ?
It's not the same shape as ones I've seen online with 4 fixing screws, it has a centre bolt to remove the cover.

Cheers

 

[WC1]

Personally I'd whip it off give it a clean, couple of cable ties and some silicon. Tuck the ends of the cable ties out the way.

 

[exedon2]

That's a key terrain access
Terrain is now part of polypipe that fitting is a 135.3G available from a polypipe commercial stockist