Doh!!! I decided to give this watch a clean, the hi-beat movements work hard and the crystal was also bugging me as it did not seem to be 'flat' on both sides. Well the crystal was sanded and polished, watch was dismantled and all was going fine until I tried to dismantle the 'do not dismantle'barrel. The lid came off easily enough but the arbor came away with the lid.. yep the mainspring broke. So now I'm looking for a replacement mainspring but may need to buy a complete barrel.