Mistake saving to SW 2013 - Is there any way back to 2012...?

Whoops.

One of our guy's slipped up & saved a needed 2012 part as a 2013 beta.

Now our assembly models warn out ( future version ).              and will not open.

I am afraid I already know the answer to this but - is there any way to save it back to 2012........????

Thanks

Rich

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