The rod is not supposed to come out of the cyclone, if it has then it has probably snapped off at the top. Using a T15 torx driver or bit, remove the 3 screws from the cyclone top and then pull it off. Inspect the area under the pull trigger where the rod attaches, if its a clean break you may be able to superglue it back together, but a better solution would be to obtain another cyclone from Ebay, you can get them for about £15 inc postage if you shop around. The bin flap will not open without the rod in place, and if you force it you will probably break it. You can push the old rod down to the bottom to engage the little hole in the latch mechanism with the cyclone top removed.
2001 was the earliest DC07, and it was made in the UK till 2002 when it was transferred to Malaysia. The problem with the earliest models is they are prone even more than usual to brittle plastics that snap very easily, and also the cyclones clog easier than later models. Look on the cyclone housing where the air exits it to go down the suction tube to the motor. Near to that port, does it have a number 1 or 2 stamped in the plastic?