The track is a little loose, is there any way I can do to tight the track?

To change the intension of the track, you just need a strong and fine tool, here I use tweezers.
1. Find the thin bolt used to connect track shoes, normally the side shown on the picture is easier to push

2. Use the tweezes to push the bolt out of the track, it may be a little tight, be careful!

3. Remove the bolt, do the same steps to remove some track shoes according to your Devastator

4. Insert the bolt back and finish!