Eheim 2217

[Nel]

I've got a question I'm hoping someone can help me with..... As per the diagram below, the pic represents my 2217 powerhead. When I installed it onto my canister, I placed the rubber 'O' ring up against where it's marked 'B'. It's a fairly tight fit and I don't think it'll leak but should I have placed it further up where it's marked 'A'? Does anyone remember where theirs sits?

[attachment=2440:Eheim_22...wer_Head.jpg]