Hi Sean, here's the other fixed up one attached. This one was a trimming boundary problem, somehow one of the edges in the model isn't there, probably another bug in some previous geometry operation but unfortunately I can't figure out where just by looking at the final result.

I fixed it by deleting the bad faces which were all around the missing edge, making new ones with the help of a line drawn in where the missing edge was at and then using Edit > Join to glue them back into a solid.

It's possible to repair an object with a couple of busted areas like this by using some "low level" surface operations like deleting faces or using Edit > Separate to detach them, then either doing an untrim/retrim of the damaged face or creating a new one and using Edit > Join to glue them back together. You don't need to remake the entire object this way.

Hope this helps! If you ever happen to catch this problem right when it happens please try to undo and save off the version of the object before it happens so I can try to repeat it over here. I'll need to "catch it in the act" in order to find out what was making the bad result and have a chance at fixing it up.

Thanks,
- Michael