I'm working on another Venus chronograph, a 140 this time. It came with a balance that had a pretty badly worn lower balance pivot and a hairspring that looked pretty funky. Some previous artisan had also filed some of the screws rather heavily, turned the roller table 180 degrees and placed the hairspring stud a 180 degrees from where it should be (judging from the mark on the balance rim). Suffice to say I managed so source a new one.

I'm a little stumped as to wether this on is original though. Or If it is indeed intended for a 140. The balance appears to be solid and not bimetallic like the one that was in the movement. It has no slots in the balance screws and is a little bit smaller in diameter. It looks lighter all in all. It was a balance complete though so it has a a spring to match. What makes me wonder even more is that the hairspring was placed at 180 degrees to what it should be. The 140 has one fewer wheel in the going train compared to most other watches so the escape wheel has a reversed rotation. I'm not sure if this has any influence on how the hairspring is mounted but this one has a left hand balance cock, with the cock closest to you on the bench. Something tells me that this balance came from a watch with a right hand configuration. The poise is also terrible in the balance so if it was factory poised, it was so for a different watch.

Does anyone know how these balances should be? Bimetallic? Screws with slots? This one isn't in Ranffts archives so I have little info on it. Google does show pictures with some variations but it's hard to tell from some of the picture quality.

All help appreciated!

Best regards