I bought recently an old Revue watch with movement 59. It was sold as non-working, and indeed that's what it was. Both balance staff pivots were broken, and also the hairspring was in such a bad shape that I decided to buy a new (NOS) balance complete when I found one.
OK, I fitted the balance on the cock, adjusted the hairspring so that it runs nicely between the pins, and put the assembly in place. The watch started running fine, the amplitude is good, nearly 300, and after some adjusting the beat error is just a few milliseconds. But the watch runs very slow, the rate is about -300.
I have cleaned and lubricated the movement carefully. I didn't find any broken jewels, bent pivots or anything else suspicious. The gear train spinned effortlessly without the pallet, and when installed, the pallet ticked nicely from side to side when pushed lightly. So everything up to that point seems to be quite OK.
Now I'm not sure what I should do next... Try to make the balance wheel lighter? Make the hairspring shorter by moving the point where it's fixed to the stud? No... I would rather get some advice or suggestions before doing anything stupid.
Thanks in advance for any help.