[HELP] How to fix poor slow motion in old PAL clip

[Miranda]

I've tried overwriting frames to TFF, BFF but whatever I try, this slow motion footage still looks jerky. Dupe frames, and some which seem to step backwards. It's from a PAL interlaced edit done back in the 1990s.

I need to remove the dupe frames and make it run smootly. Any suggestions?

Sample clip