Hi
There is not a lot you can do if the vhs copy has bad tracking, the frame judders or there are wavy playback effects rippling up the screen. You can remove the scanning defect often seen at the bottom of the frame or wavy edges to the frame by cropping these defects out. A shaky film may show some improvement if it is stabilized but you can only do this once. If you want to repeat this process you will need to export the project and then reload the export and run the stabilization a second time. However you may not see a great improvement.
Nat