Landeron: Minute chrono hand moves back when chrono started

[watchfellow]

Hi everyone, I have a Landeron 149 movement with an annoying problem I can't figure out. When the chronograph is pressed the minute chrono hand moves back slightly, throwng the minute recording off. Observing the movement, I can see that the sliding gear moves slightly when I engage the chrono, shifting the minute runner. I made sure that the central runner dart does not hit the sliding gear when I start the chronograph, so not sure why the sliding gear and minute runner are moving.

Getting the eccentrics right on this one was a pain, so before I go adjusting them again I was wondering if there might be another solution.

[nickelsilver]

Try moving the minute finger on the chrono runner a bit forward (counter clockwise looking at the movement side). When the sliding gear comes down it's catching it and moving it backwards, then the finger trips a minute in the first few seconds.

[watchfellow]

Thank you silver. The minute counter seems to be working properly now.

However now for some reason the stop function doesn't work now. I can start the chrono, but cannot stop it. I can manually move the Chrono to the stop position, but not with the pusher button. The return pusher works fine. I've attached a photo of the movement with the chrono off and with the chrono on. 

Edited January 25, 2023 by watchfellow

[nickelsilver]

You might already know this and there's another issue, but this chrono does both stop and zero with the zero or flyback lever. Start with operating lever, stop with flyback, then you can start again with operating lever or zero by pushing the flyback again.

 

The function of that lever is a little tricky to adjust if needed; when stopping, it pushes the operating lever down, which moves the cam/hammers toward the center- the end of the flyback also acts as a stop, keeping the cam/hammer from going all the way to zero. When the flyback is then released, is should return to its neutral position. If it is restricted from doing so, some careful filing is necessary where it's contacting the cam/hammer to allow it. Not too much, as the contact with the cam to zero is very small. Before filing anything, check that the cam jumper is fully seating in the notch for the wanted position first. If it's not, find out why and fix it. Which brings us to:

 

These movements can be very particular about lubrication. Everything that moves, slides, pivots, needs to be greased in the chrono. There are numerous shouldered screws holding things down and acting as pivot points, these need to be greased. Also check them for freedom with their part; there are several that are the same (the ones just holding things down), but they may have been adjusted for a particular location and switching them might mean binding of a part. If a component was replaced, the associated screw may need adjusting by undercutting the head or the shoulder with chrono screw cutters or in the lathe.