weeping PAS reservoir

[Richie-Van-GTi 81 2 Cars]

Has anyone known a reservoir to weep? I thought it was my pipes or rubbish pipe clips that had caused a leak while the car has stood over winter. 

Just cleaned it all, replaced the pipes and clips so all new and tight but I still have a leak. 

There is fluid sat on the lip half that runs around the resevoir about half way up, wondering if the resevoir itself could be leaking somehow? 

[Leslie green 160]

Its more likely to be leaking from the cap  and running down id have thought but it could be cracked 

Edited March 21 by Leslie green

[petert 630]

Take it off, clean it and pressurise it with 5psi. That will soon tell you.