I have a brand new F+ and a 35mm back. When I try to install the back, the little cross-shaped device at the top of the take-up spool fails to engage reliably with the little paddle sticking down from the winder knob. Instead, it gets pushed down, resulting in the 'film release' being pushed down and outward. I'm obviously loath to apply a lot of force to all this plastic. Has anyone else experienced this? Could I be faced with a manufacturing defect?
The answer is that Lomo has a manufacturing glitch and shipped some incompatible back/body combinations.
I spoke to their support line, and they explained that there was a manufacturing error with some units such that the back and the camera aren't compatible. They've send me an RMA to replace one or the other (I'm momentarily a bit confused about which), and I trust that this will resolve the problem.
Lomography knows about this issue and they are still sending it with the Diana kit. I contacted Lomography, they acknoledge the defect, they sent me a "repair kit", two weeks later, it still hasn't arrived. They have a very poor customer service so be prepared to be disappointed.