Richard, now for your second repair!
That tube is the tube that feeds fuel from the float bowl to the carburetor jet. On the inside of the brass nut, on the end of the tube, there is a little brass washer, and a rubber 'O' ring. When you tighten the nut, the 'O' ring expands and keeps the tube in place. My guess is that the 'O' ring has deteriorated, allowing the fuel leak. You could try to snug the nut up a bit tighter, but not too tight. I would take the thing off, and see what shape the seal is in. Sometimes when you remove the tube, the seal will stay inside the float chamber body, and you will have to hook it out with a pick.
You may be able to find something the right size to replace it at the local parts store. If not. Victoria British, Moss Motors, and several other places sell them separately. Maybe some of our Canadian members can help you out, as the things only cost about $2.00 US apiece, and it would kill you for shipping from the States. Mr.Mini, in Stony Creek may be able to help you. The carburetors are SU, HS2's, by the way.
Jeff
[ 03-20-2004: Message edited by: Bugeye58 ]</p>