The Dark side of the force said:
the colours seem slightly off; blacks are more grey

Try to adjust the levels in Virtualdub; the best would be to use a proper calibration disc, or at least a test pattern; if you haven’t one of them, find out a black frame, then a white frame, and adjust levels accordingly to reach the “borders” of the histogram.

Some info on analog capture: https://forum.fanres.com/thread-933.html

Even if I encourage you to continue your mission, you should be aware that laserdisc (as much as I love it, and I DO love it, a lot!) is not the best version available; waiting for 35mm preservation (that would be the best), you can find out SDTV captures that are better - GKar and TB for all the three episodes IV, V, VI.