When tightening the track, it sometimes takes more pressure to push the grease inside as you can’t get any more into the valve. Instead, the grease will leak between the grease valve and the grease gun. There may be two issues.
The first issue is that the end of the grease gun is worn out and not sealing tightly on the grease nipple. The second issue is that the grease nipple has been damaged from corrosion, rust, foreign debris, or tools as the grease gun cannot get a good seal. To solve these problems, you will either have to replace the end of the grease gun or replace the grease nipple on the track adjuster grease valve.