X350 2004 V6 Rear Suspension noise

Hello Folks,
My X350 2004 V6 has developed a “graunching” noise on the rear n/s wheel (rhd). I can reproduce it while stationary by pushing up and down on the rear wing. Before i get into removing the rear air strut wondered if anyone has had a similar issue and what the solution was? Any advice appreciated…Rgds.