I can't be arsed to go digging but there have been a few instances discussed on here over the years.
He does seem to have a blindspot when it comes to seeing antisemitism, but he doesn't seem to dig his heels in and defend it once it is raised, which is I think the more important thing.
This is most famous case I think.
The issue of anti-Semitism in the Labour Party has resurfaced again - and this is the reason.
www.lbc.co.uk
Not a great look for him, but would have been so much worse if he had stuck by his original comment.
Also that is a shit article, just the first I found.