HI guys -I have a Waltham question for you- I just got a 1935 Waltham 23 jewel vangard serial # 28879850 Ive been timing it -how long should the mainspring run --thanks BOB

I would think that it would depend on how good the mainspring is. If new should last about 36 hours. If not then it will be less maybe even as low as 12 hours.