CUORE 850 1988 model Gearbox - won't engage in first or second


Can anyone assist, problem occured overnight, gear stick won't move into first or second - physically will not move to th eleft up or down. Took off the rubber gator internally & unhooked the LH linkpin and the gear stick moves fine freely, so the problem is either with the linkage or internally to the gearbox.

Has anyone experienced this or is the issue simpler etc...