Horological Meandering

The Engineer
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Technical question - your kind assitance

First I would like to introduce myself. I am a Machine Design and Manufacture Industrial Engineer.  I took up Watch Smithing abut a year ago as a hobby.It keeps me busy during my free time.

Now to my issue, I genreally work on Manual Winding Movements and some Automatic Manual Winding Movement's like; Lemania Movement's, ETA manufactured 28336-2, 2824, 2892 etc...Some Hamilton's, Gruen's, Elgin, Tissot, Patek's and a couple more. I tend to stay away from 7750 Movements since they all give you a bit of trouble every now and then.

Presently I ran into technical problem with a Genuine Valjoux 7750 Chronograph. I have one I use for spare parts. Now my situation is that the watch winds power well either by hand or rotor. If I leave the watch face down it will work perfectly, on time and for about 40 Hrs., As soon as I flip over the watch over, it comes to a stop in less than 30 seconds. As I over looked the Movement without the rotor on I shook it a little bit holding it next to my ear and I heard what sounded like a loose part but I could not pin point from where it came from. I did the same procedure with my replacement parts movement and you could also hear as if a loose part was inside, however the noise on the semi-working movement did sound much louder.

I checked the Balance wheel with a tweezer, very gently checking if it was out of place, but it was firm. The Coil is well and working as I mentioned, otherwise it would not run at all. So before I start taking apart the movement I would really appreciate some suggestions and things to look for. It is a friends watch and right now he is low on cash and the dealer was charging him a ridiculous sum just to overlook the movement and a base tariff for fixing it, should no spares be necessary..So I am in a bind, I have never had to fix a watch with these symptoms.

So in brief, The movement works perfectly, and as soon as you turn it over you hear a slight noise, which I had not mentioned and 30 seconds later it comes to a dead stop..? The movement is genuine and came out of a Hamilton Stop Watch and it is your basic Valjoux 7750 Stopwatch Movement. I would really appreciate any suggestions, comments or if someone has had the same problem and fixed it would be of great help and value to me. This is the second time a go into a 7750. If you could point me out to where I can find and download a parts list and "Assembly / Disassembly Schematic's" to help me out with this annoying little problem I would really appreciate it.

Thank you,
Sincerely,
Engineer Daniel P. Hudson