strecthing model data im not totally sure.
one other problem you may be facing is proper rotation.
are you plotting more then one keyframe for the rotation.?
imagine starting the limb at rotation zero.
then rotating to the keyframe and degrees 179, then
reapeating hte process up to degree 359.
most animation packages will just animate from degree zero to degree 359 but it will take the shortest path and appear not to animate, when all it has done is move 1 degree to achieve the result.
adding the keyframes will help in the animation path process.
If no-one gives your an answer to a question you have asked, consider:- Is your question clear.- Did you ask nicely.- Are you showing any effort to solve the problem yourself 