Ok here goes, remove the plastic cap over the hinge of the binocular where the tripod mount would go. inside the whole you see is a flat screw that needs undoing. With a scredriver about 2 mm blade width feel for the screw and undo it. The screw will not fall out of the hole. adjust the focus untill the focus arm pushes the oculars over there guides and withdraw the two arms and worm screw. Block the good side of the binocular with a lint free rag and with a strap remove the ocular guide on the side that is out of collimation. Then remove the small cap screw that holds the prism cover on. Remove the prism cover and carefully examine the prism and its seating. You are looking for a prism that has jumped out of its seat.