how to fix a wobbly shifter?
 

so my 300zx is manual and the shift knob is really loose and wobbly in any gear..
need help on how to fix it this issue.

A couple things to check. Remove the remove the radio panel and radio. Then remove the shifter panel. The shifter will come out with the panel also.

Next check that the plate that holds the shifter still is not loose. I had the rubber dampened dry rot and break one time. Made the shifter fall down. If that is ok then remove this metal plate and check the single nut and bold holding the shifter to the shift linkage. Then check the shift linkage for damage and IIRC it has two bushings toward the transmission.