M4 close focussing problem

I received a lovely M4 today - great condition. It was a birthday present from my wife and now we have matching Leicas and 35mm Biogon-Cs.... yes all very quaint

Anyway, it's all great but there's an issue with close focusing. The RF patch doesn't focus closer than around 0.8m. Have seen this with M3s obviously, but my understanding as that all M4s came out of the factory capable of 0.7 focussing. It's not the lens - we've tried both on each camera... my wife's M4 focusses normally with both, but mine will only focus to 0.8.

Any ideas? Easy fix? CLA is not really something I want to do right now.

Thanks,

David

I just checked my M4 with a Zeiss 35 f2.8 lens that goes down to .7m to check and it will focus that close...at least with that lens.