S212 tailgate groaning noise

[MrCholmondeleyWarner]

Anyone else had this? A groaning noise from the tailgate when opening or shutting - more pronounced when shutting. I've tried lubricating the strut pivots and also the strut shafts, sometimes it shuts up for a while but always comes back. Is it likely to be the struts or would I be wasting money replacing them, only to find it was something else?

Many thanks

Nick