Setting date on Sub

[ratty]

Hello

I have an older style Sub date, probably about 6 or 7 years old, and I'm having some strange problems setting the date.

When I turn the hands to set the date there is no problem but when I use the quick set function there is. I know when you use the quick set function you are suppose to change the date in the afternoon so that it will advance the next time the watch goes past the 12 o'clock position but when I do this it really is hit or miss if the date changes. No matter how or when I use the quick set the date usually changes when I don't want it to! I have asked about this at my local Jeweller and he suggests a tooth may be broken in the watch. The watch is used in rotation with others so only gets used perhaps once every 5 or 6 weeks. I don't know how the quick change physically works so I can't guess what may be wrong and this is why I am asking for advice. Is it possible a component used in the quick set is sticking somehow which would not show when the date is set by turning the hands? It this a service job?

Thanks in advance.