The only way I found I could get a 100% reliable 3:2 pulldown removal is to use VirtualDub in manual mode, finding out what undo setting works at the start of the movie and for how many frames, save that section as a new avi (direct stream copy) and press del, then start again with finding out what setting works and for how long and saving it - repeat until the whole film has been cut down into sections with each section having their own 3:2 pulldown removal setting. Falling back to AviSynth and the Decomb filter for small sections where VirtualDub just can't seem to find the undo setting.
Then process each piece individually by VirtualDub's job capability and join the now ITVC'd cleaned sections together to create a final complete film. Slow yet, laborious yes but it's the only 100% reliable way I know of removing 3:2 pulldown, AviSynth Decomb filter and VirtualDub's automatic removal can't do the job 100% reliably, AviSynth Decomb comes close but not close enough so I use it to get a good-enough 23.976fps source to test cleaning filters on.

I've done this process on a few NTSC laserdisc captures to create progressive NTSC DVDs and PAL DVDs, usually end up breaking the captured avi into between 5 and 15 pieces, one day I might put fingers to keyboard and create a guide on how I do the process.