A retired photo journalist said to me that when they were using Zeiss Contaflex SLR and when they were not working properly, they used to throw them on the concrete floor at a moderate angle so that they could slip and the wall would stop them. And that was usual for them to make the cameras come back to life...😱
As you've guessed, they did not like these cameras very much, and they were waiting the new F Nikons for replacement, they treated them with much more respect.😀