I would gently palpate the affected area....basically all you do is slide the snake's enclosure so there is an opening big enough to crawl down into. Place the snake's head just inside so he sees his way back in an starts to move. Place your hand in such a way that your thumb runs along the back of his spine and your other 4 fingers run along his belly. As he moves, gently squeeze your hand shut so the snake has to flatten himself slightly to move through. Basially the same way you'd feel for follicles. Again, be gentle, repeat a couple of times, and you might get things moving.