I really couldn't tell you what to do to fix this yourself, aside from letting it grow out as much as you can.. Or enlisting some help. A few issues to keep in mind for next time (I've never completely body clipped a horse, I have body clipped hundreds of dairy cattle though)..
My biggest issue is that your horse is dirty.. Its hard on the clippers, for one thing and clippers can sometimes be an investment. Second, you're clipping all over. You want to use long, sweeping motions with your clippers, against the lay of the hair. You also want to keep the clippers flat and level along the body.. Not digging in anywhere. Your blades are not sharp enough.. Get them sharpened and then learn how to adjust the tension in your blades. If your clippers are getting hot, they're probably too tight, which will dull the blades really fast. If its too loose, it won't clip well either.
To fix up the areas you couldn't get before, I'd suggest you start desensitizing your horse to the clippers, now. Turn them on and keep them near (not on) the trouble areas until she doesn't care.. Get closer and closer and eventually hold them up against her (not actually clipping anything). Be gradual and reward her when she relaxes, shut the clippers off.
I'd get to practicing as much as possible before the next show too.
Last edited by soileddove; 09-13-2012 at 03:46 PM.