I have been using the OM4 quite a lot, mainly for colour work; so far it has worked well. On a recent film, however, I found I had numerous blank exposures, even though the camera appeared to be working normally. Then it started to lock up, as if the batteries were flat, even though, on investigation, they weren't, and the camera wouldn't respond to the normal unlocking method, turning the shutter speed to "B". Needless to say, this behaviour couldn't be repeated at home, only when out with film in the camera!
After some fruitless fiddling and cleaning of contacts, followed by outdoor failures, it suddenly occured to me that it is quite chilly outside now; so I loaded a scrap film and stuck it in the freezer for ten minutes!
When I got it out, it fired off four frames apparently normally, then locked with no viewfinder information visible, and would only unlock by removing the batteries, as I had seen when outside. This happened twice more, each time having to remove the batteries to reset the camera. I think this would indicate the electronics are frazzled, possibly a temperature dependant fault. Repair isn't really an option; I would need a donor OM4, in which case I may as well use the donor instead. I may wait for warmer weather to see if the fault disappears; or perhaps I should stick to clockwork cameras!