The whole Corbyn anti-semitism case would be stronger if they didn't also use his or Labour's criticism of Israel as being anti-semitic.
Most of his criticism of Israel is just standard, boilerplate lines from the pro-Palestine movement, but there's numerous instances of his criticism of Israel being anti-semitic (e.g. when he concocts conspiracy theories about Israel and blames it for conducting false flag terrorist attacks in neighbouring Islamic countries).
I don't think that Corbyn himself is anti-Semitic but I do think that he hasn't done enough to purge discrimination from within the party. That's the main criticism I have of his time as leader.
I used to think he was just an idiot who liked to join protests, but he's used the 'I'm just thick' excuse too often for it to be true.
-Supporting an antisemtic mural? Claims he didn't bother looking at it closely enough.
-Appears on platforms with Holocaust deniers? Claims he didn't research these people before agreeing to speak alongside them
-Inviting antisemites for tea in Parliament? Says he wasn't aware of their views or was simply 'promoting a dialogue' (he's never invited anyone from the pro-Israel side for tea in Parliament, so this 'dialogue' is with his own side...)
-Joins antisemitic Facebook groups? Claims he didn't look closely enough at the content
-His association as a paid presenter with the antisemitic media group Press TV? Claims ignorance
What probably did it for me was his weird obsession with 'Holocaust Memorial Day'. He once called for the word 'Holocaust' to be removed from Holocaust Memorial Day...on Holocaust Memorial Day itself. In a different year on Holocaust Memorial Day he hosted an event that compared Israel to Nazi Germany.
Essentially I'm done giving Corbyn the benefit of the doubt. It's just too much smoke for there to not be fire.