I discovered a design fault with the New Canon F1 yesterday that although i've been using them for more than 25 years, I recently bought a Canon AE motor drive FN so I could get shutter priority AE in addition to the aperture priority AE that the AE prism gives, and I have three of these F1N-AE bodys so I thought since you can't remove the motor drive with a film in the camera without exposing it because the film chamber cover screw has to be removed from the camera base to fit the drive, so I thought I could leave the drive permanently on one body which would solve the problem, but I discovered that if the camera battery fails with the drive attached to the camera it isn't possible to remove it and although even if the battery fails you get a full fill range of mechanical shutter speeds from 1/90th sec to 1/2000 sec. you need to be able to remove the battery from the camera first before the camera can do this which is impossible with the f***ing motor drive attached.

So I discovered this issue as well. I have a black film changing bag with me most of the time. If my camera battery dies in the middle of a roll of film, I take the MD off in the film bag, change the battery, and put the MD back on in the film bag. A little bit of an inconvenience but it reminds me to carry fresh batteries and check the battery before loading a new roll. Having said all that, I've only had a battery die, in the field, once.

I have since found out that if you use the Power Winder FN instead of the Motor Drive FN there is no need to remove the rewind coupler cover when you attach or remove the winder to fit a new camera battery because the winder doesn't give power rewind for the film, it has to be rewound manually.