Hi, I have a 1976 computron N6, one of a pair I had. Just sold the first and was looking to do the same with this one so have been monitoring it over a week or so with fresh batteries (357s). It was spot on for about 4 days but then when I pressed the button the time was a few hours previous, the LEDs stayed on and the time remained the same until i took the batteries out. No combination of buttons would 'unfreeze' it. Now when i try it, it lasts only hours before staying on.
I can see no indication the buttons are sticking, travel really freely and precise. I tried some thin film inside the lid of the case (to make sure the insulation layer was ok), made no difference. I've used LR44 batteries, no difference. All the battery contacts are good. the inside serial number is 2293.10. I just wondered if anyone had come across this before, LEDs staying on and time staying the same until batters removed.