After a bit tinkering and fiddling with the regulation screws, I managed finally to get it right. I had moved inadvertedly the regulating excentric screw of the minute recording jumper (part 8270), the one GuiBer refers to.
I repositioned it so that now the chronograph runner (part 8000) hits perfectly only 1 tooth on the sliding gear (part 8100).
The movement is now complete and working perfectly. Finally... :woohoo-jumping-smiley-emoticon:
I am uploading the video and will post it ASAP.