Goosed..

So the Tamron 70-300 I replaced with the Sigma 150-600 met its maker today. It had become suck on the D5100 that Joshua is using for college. I gave instructions down the phone and a FaceTime call to help remove it but to no avail. I had a look when I got home from the daily grind and it appeared the housing is coming apart, so I'm guessing something is sticking. With limited force applied ....I managed to get it off....and then put it back on to see if it was a lens or camera issue! AAAAARGH WHY!!!??
I got it off again....
I've decided to dismantle the lens for curiosity!