Thanks Grumpy but there is no way that the rope will unwind as shown, the gap between the drum and the housing is far to small and even trying to insert a blade there to open it up a bit is fruitless. So I removed the plastic, which came off easily enough and used a g clamp to hold the spring pack in place. I then loosened the centre retaining bolt and wound extra tension onto the spring with a pair of long nose pliers and retensioned the bolt. Seems to be a lot better, could probably do with another turn but it retracts pretty well now. Just have to pull the carby off now and clean it out and another mower (the Morrison from another of my posts) saved from the dump.
