Officers have recently seen CCTV footage of the assault on Oak Lane, off Hanson Lane, which shows the man trying to get away from a group of men.
The victim was wearing dark clothing and an orange hat and was carrying an orange bag in his hands and a dark blue bag on his back.
The attack happened between 8.30pm and 9.30pm on Wednesday, June 1.
Anyone who can help police find the victim should call police on 101, quoting 13220313886.
Information can also be passed on anonymously via Crimestoppers on 0800 555111.