I bought a Marubi watch. From totally wound down, it winds as normal for quite a few winds, then it makes a sound which sounds like the end of the mainspring is not attached just being pulled away from where it would be attached and making a bouncing sound off the rest of the spring. No idea if it is that at all, that's the enquiry. It seems to run ok, but the watch only arrived 12 hours ago. What's going on, will it be a usable timepiece as it is? What sort of percentage power reserve will it hold?