Hi Peter,
Thank you for your reply
I used Isopropyl IPA 99%, (which I have used on the electronics on the computers I use to build) not noticed movement from the contact block. I only had this issue when I hand held recently, as I do 50/50 with a monopod. I will recheck all areas of the lens contact to the camera housing, I will recheck in daylight.
Many thanks
Stay Safe
Best Regards
John