I just got a 75 G4 and I think I´m missing the part of the dual range shifting mechanism. It seems that there should be a plunger inside of some sort that is activated by the cable operated lever (part outside the box and part inside). The gears are there, and the inside lever but nothing for the lever to push or pull on, no springs either. Does anyone have a blow up picture or drawing of these workings so I could identify what parts I may need? Thanks