I bought a mamiya 6 a while ago and am finding that more often than not (although by no means everytime), when loading a film, the arrow on the film backing overshoots the marker in the camera back by about 1 -1 1/2 cm. this leads to me losing about 1/3 of the last shot on the roll ... am I doing something wrong in loading? I load according to the manual and always use ilford films - I've heard of similar problems with Ilford films and hasselblads .....?