I have a 16s.15 Jewel Waltham,serial no.12112743.I changed balance staff,"friction fit" staff and roller jewel.Runs with good motion but lost 20 minutes over night.Main spring looks O.K.It's been cleaned oiled and I can't see anything wrong with it.Any ideas would be appreciated.Thanks.Norm

Norm,

Food for thought:

I always do the demagnetize on a movement after touching it will screwdrivers (you have probably already done this step)

Does the hairspring have any coils rubbing against themselves or dragging on the balance wheel itself?

Hopefully noone has added an extra set of balance weights during the life of the watch slowing down your watch (usually 7-12 minutes per "average" size weight during a 24 hr span).

Sure there are many more possible issues, but these are some I have encountered

Pictures always help. free-Spin of Balance Wheel, Powered free spin of wheel train (mainspring, Center wheel, #2 wheel, #3 [seconds] wheel and #4 [escape wheel]), Beat, Balance, Poise, Magnetism, Hairspring not in between regulator pins are all "just for starters reasons it might run sloooow after your service.

Norm

One other possibility is a slipping canon pinion.

Thanks for your input guys.I've been checking all those things.It only lost about 5 minutes last night so I'm getting close.I 'm going to take it apart one more time and check for dirt.It was really dirty and my old eyes may have missed some thing.Regards,Norm