This tool saved me lots of time. So I thought I point you to it:
Among some other nice features, my favorite is repair
Repairs a broken Hyper-V snapshot chain where an administrator has expanded the size of the root VHD. The base VHD will be returned to its original size. THIS MAY CAUSE DATA LOSS if the contents of the base VHD were changed after expansion.
I am not able to open the above link.