I've been having fun with the fermentation mystery too. I started making wine for the first time last summer and in September made some raspberry. I was hoping to bottle it about now as I figured it MUST have stopped fermenting after so many months. I swapped the airlock for a solid bung (can't remember precisely why!) and am glad I checked it as when I took the bung out a few days later it came with an almighty POP! I gather from this that it is quite definitely still fermenting (solid bung swapped back for an airlock!). Can't see any bubbles though even after staring myself dry-eyed gawping at it for long periods. Will have to get the hydrometer out and be technical, I guess. Perhaps it was the cold winter: the average (indoor) temperature in my flat between October and March is 10 degrees centigrade. And no, I don't have an airing cupboard. The warmest place is in bed and I'm not sure I'm going to resort to sleeping with my demijohns! Perhaps the wine went into hibernation and only just woke up... Otherwise I was relying on lots of months and several rackings to have gone by to know that it had stopped fermenting. Ah well. Scientific method wins...