[Gegrad]

Bent axle? I had a bent axle on my old Pasport and once I replaced the axle it towed better. I did not have the random swaying your are experiencing, but the trailer was generally more stable once the axle was replaced. I suggest this because your swaying is random; it could be the combination of the bent axle and particular road conditions at those random spots cause you to observe the swaying, then it disappears when the road conditions change back. Since you can't see the road conditions (subtle variations not visible) that could be triggering the swaying when the bent axle hits those conditions. Just a WAG.
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