: I have not noticed that something is missing from the mech. not too
: familiar with those, I'll ask if working...

Yes, definitely ask whether the chronograph stops, starts and resets to zero correctly as well as the watch keeping time ok. Like I said, I'm not familiar with the movement, but some of the chronograph operation parts at least aren't quite where I'd expect them to be.

: Please, send a picture of where/how is the Valjoux logo placed.

Here it is on a Valjoux 23, underneath the regulator - the movement reference and then the symbol for Valjoux. These weren't on many of the earlier movements, so it could just predate that practice.

Not sure about it saying "Swiss made", off the top of my head I only remember Valjouxs saying just "Swiss", "Switzerland" or omitting the wording altogether.

: What bothered me was the Heur logo being too close to the 20 on the
: face,
: and the alignment of the Heur sign on the mech., the 17jewels is
: nicely curved along the line,
: the Heur Co. sign is placed straight not following any of the
: lines...?

Yes, the Heuer logo does look off. I have seen that before, with the shield being closer to the 20 than the 10 but don't remember whether it was this same watch. I'd say the dial definitely has been retouched, we're not seeing any indication of the 60-odd years of age the watch has. Plenty of period-correct touches though, like the "Made in Switzerland" text. The markings on the bridge are oddly aligned, but we see quite a lot of variation in these, especially in the earlier years. Here's a later Valjoux 92, showing how its similar-looking bridge is marked:

: The logo on the case .... that beats me, I have no clue how that
: should look..

Again, this varies a lot. The "o" in "& Co" is usually lower case though, rather than the upper case of this one.

: Thank you for your help!

I'm not sure how much help I'm actually being! It's not one where I can be definitive, I'm afraid - plenty of Heuer or at least Heueresque touches but a few question marks too. At the end it comes down to how much is being asked, I guess - cheap enough and it's worth a punt, expensive and it might be worth looking at a watch we can more easily authenticate.