@KE

(1) Yes I've seen the creation of a snapshot, but the question is not only the error with the same model, but if you open a new scene and try to import a new ms3d file, you get also an error. I think it is important to remark the need to a reset in case of getting an error using the script. If not the users will think the importer doesn't work.

(2) Yes, that's the question. I didn't know that M2TW models are using always the assignation to two bones.

If you need more information about 3ds max, don't hesitate to ask me (even if I'm not an expert, I'm simply a user that tries to make everything as easy as possible )