Sounds like it should probably go back to Josh. However, this process takes time and cost. So if you are in a hurry you could always try to get it repaired here. Where are you located? Will help to point you towards a reputable repair or watchsmith. What movement in your UPO? Depending on the movement the repair may or may not be worth it. Chances are good that the repair will be simple but if it is a 21j then often it is cheaper just to replace.
Very nice J! One of these days I will get around to completing my membership application as well. Finally finished mine off last month but have been waiting to take some good pics.
I agree with FxrAndy, doesn't sound necesarily like there is a problem. Based on your description it seems normal for a unidirectional winding automatic. It is common for a watch's time keeping to vary between wearing it and being on a table. Not ideal but common never the less. How much time does it lose while you are wearing it?
Either that or the autowind mechanism is not doing it's job correctly. Perhaps it might be better if you can explain more detail of what is happening. Circumstances, what you are doing, what it is doing, etc.
Great stuff. Really odd that damage to the main plate. I cannot even imagine the circumstances for this to occur, or the tools used. Thanks for sharing this with us.