Once a gear shifter becomes loose, it cannot be tightened. The lower gear shifter bushing will have to be replaced to remove the looseness of the gear shifter. The gear shifter is connected to the transmission linkage underneath the gear shifter console. Generally, most all gear shifters will become loose due to aggressive gear changing from the gear shifter. Aggressive gear changing can cause damage to the bushing on the bottom of the gear shifter lever. Once the bushing is damaged, it will cause slack in the gear shifter. Always move the gear shifter without slamming it into gear.
Remove the bolts and nuts that secure the center console around the gear shifter with a 1/4-inch drive ratchet, a metric socket and a Phillips head screwdriver. This will expose the rubber boot. Pull back any carpet as needed to make room for the rubber boot to be pulled over the gear shifter.