Just installed a new Mainspring for a pocket watch barrel and it hooks onto the outer rim of the barrel. My problem is that once the spring is pushed into the barrel the centre arbour was hooked by the spring started to slip once it reached a little tension. This would indicate that the spring has unhooked or was never hooked to the outer barrel rim. Are there any Tips for making sure that the spring is actually hooked on the barrel? Sent from my iPhone using Tapatalk