On my 2-78 backhoe (nee Oliver 1650 tractor) the shuttle shift pedals will stay engaged in whatever direction that I am going, even when my foot is off the pedal.  Is there supposed to be a spring or something that would return the shuttle shift to neutral when my foot is off the pedals?  As it is now I have to press the opposite pedal to disengage the shuttle, and it makes running the machine a pain sometimes.