Position the IS lens assembly over the intermediate barrel. The spot that the white cable comes out of the IS assembly should be positioned just left of the focus window.

Lower the IS assembly all the way down into the intermediate barrel.

The intermediate barrel is slotted in a way so it is impossible to insert the IS assembly in the wrong position. If the IS assembly is not going into the intermediate barrel all the way, it could be because of this.

Be very careful with the ribbon cables on the inside of the intermediate barrel. Ensure that they are laying up against the walls of the intermediate barrel as you insert the IS assembly. There should be indents on the inside of the barrel for them to lay up against.

Screw in the three M2x8mm Phillips #00 screws to secure the IS assembly into place.