I realised that this was the first time that I used it since I bought it about a year ago so it has never worked for me. I've used a 90/4 for several years with good result but a friend borrowed that one and I picked up my untested 90/2.8 for the trip (I've learned something about that). Luckily I took most of my photos with my xpan.
Jim, thanks for the tip. I will check that the lens head is correctly seated when I get home tonight.
Gerald, thanks. I have no knowledge of what has been done to the lens by previous owners so this is a strong possibility. If the head is seated correctly I will consult a repairman.
Thanks for the feedback.