Hi, sorry for the late reply, it took a while to remember my password. for the spring, i used a 200mm 4.5mm OD extension spring from ebay,:
4.5mm OD Stainless/Carbon steel Tension spring up to 1000mm long. These springs can be supplied to any length up to 1000mm. Tension springs. If no further instructions are given, all springs will be cut to the ordered lengths i.e. 2x100mm & 1x50mm.