Is it leaking from where you've circled?
There must be a seal behind that.
Indeed, might have to get number 6
1 Attachment
There is the element seal/o ring. Undo the 3 hex nuts and you'll see it. Fit a new seal and you should be back in business. You may get away with just tightening the bolts!
@anidel started
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Is it leaking from where you've circled?