regrouping a model in MS is work. There is no short cut. The best approach is
1 - get a piture of coffee ready
2 - select some faces (don't worry about perfection here)
select regroup and then hide them
3 - continue until the entire model has been regrouped and hidden
4 - now, take a break and get ready to put it back together
5 - go through each new group and look for mistakes. There are some.
6 - If a group has a piece that belongs in another group, select the bad part and regroup it. hide that part, Hide the current group, Show the group the part belongs in, select it. Show the bad group and select it too. Insure only 2 groups are selected and press regroup. that will attach the bad group to the group it belongs too.
7 - refill your coffee and repeate for the next error spot. Fun eh?
8 - when done you should be ready for texturing .....
internet gaming group