Hi everyone.
Have the same problem here.
I've bought my 645e on eBay from the US seller and its viewfinder shows no infinity, although at the film plane it's OK.
I will not ship it back because in that case I should pay for the shipping and it's expensive here in Russia where I live
I have searched through the internet for similar problem discussions and that thread is the only one I found.
I intend to try to fix this by myself as I have some basic experience in camera repair.
Would the pics of disassembly process be useful here?
Sadly, I had no success trying to find any service or repair manual or disassembly guide for the 645e so I'll be all alone.
BTW, I found that 645e HAS INTERCHANGEABLE focusing screen!
Remove the lens and look inside up along the lens mount plane. You'll see small metal "L"-shaped hook that locks front edge of the screen frame. Gently pull it to the left with a toothpick or something and it will release the frame with the screen giving you the ability to take the screen out for cleaning or replacement.