it turned out relatively easy to disassemble the 10-22mm down to it's USM, with only 8 screws, 4 ribbon cable connectors (easy to reassemble) and one pressure plate, all doable with a single small philips screw driver. what i found was that, the distance scale (attached to the ring that rotates the focus elements) is sandwiched between the manual focus ring and the USM motor. there are 3 wheels on the distance scale ring which isolated this ring from the manual focus ring and the USM ring motor. This wheel mechanism allowed both autofocus and manual focus to operate simultaneously.
After much stumpedation and precarious fiddlation, i realised that if i pressed the USM ring motor onto the focus ring a little harder, the focusing would work again! turned out that right above the USM was yet another ring, which when rotated, will vary the pressure holding the USM onto the distance scale ring. i rotated it about 3mm clockwise, and voila both auto and manual focus worked again!