You did not attach the model...

Does FreeCAD have access to the web? If you drag a link over it (like a file from the forum) it should download it.

I think that in the first clip you are actually dragging the line very close to the point. See the second drag in the following recreation:
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I remodeled this in PartDesign. Not sure if the dimensions are correct because I overlayed the sketch (with maximum zoom).

urbjof wrote: ↑Wed Jan 27, 2021 3:15 pm the dimensions were all moved all over the place.

Read about the topological naming problem

I was thinking more like this:
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Springy bump (note the cuts) in the rotator and indents in the adjuster.

VI-Suite for the lazy ones

ractive wrote: ↑Tue Jan 26, 2021 8:34 pm Is there an explanation why this "wave" results?

There might be some explanation deep inside OCCT documentation. And I bet Ghris_G has an idea...

NaviBlue looks better. I have some remains from a theme there but that just improves readability (despite being ugly ).
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No idea why a Mac would do that. I just tried WinRAR under windows. Opened the FCStd file directly, double-click the Document.xml, opens in associated program or chosen editor, changed a sketch label, closed the editor/saved the file. WinRAR detects the changes, suggests to replace file in archive -...