A man who randomly stabbed two people on a Melbourne tram last July remains on the run, leading to a fresh appeal for information.

It is a crime puzzling detectives who on Tuesday released new CCTV footage so that anyone with an insight or clue might come forward.

"We need to solve this so it doesn't happen again," Transit CIU Detective Senior Constable Mick Keane said.

The attack occurred on a crowded route 82 Footscray tram travelling along Droop Street about 8.45pm on July 28, a Friday evening.