Landeron 148 chrono hand stutter

[watchfellow]

Hi everyone, I just put together a Landeron 148, but find that the chrono hand does not run smoothly when the chrono is engaged. It seems to stutter at odd intervals. I am assuming the issue is with either the runner, driving wheel, or coupling clutch, but am not sure.

I have looked over all three and don't see any obvious issues with them.  I have also tried to adjust the depthing as best as I could. Playing with it I don't see any improvement on the stuttering. It is almost like the ratio on the wheels are off... I know that some parts are interchangeable between the different Landeron calibers, but not all. Could one or more of these wheels have been incorrectly substituted?

I am attaching a photo in hope that someone will be able to offer help. Thanks in advance!

[Delgetti]

Hm, is the friction spring fitted correctly with slight tension:

 

https://watchguy.co.uk/cgi-bin/media?image=P1090695.JPG&email=&wat_id=3515