It's a simple bucket with cork and air seal, the one you add water to and has a red cap. It's been happily bubbling away, and if I put very gentle downward pressure on the lid CO2 bubbles out the airlock, so no clogs at all. I've no blow off tube, I never had a huge amount of foam nor do I now...
So I took final gravity readings two days in a row and it was identical (OG was 1039 and FG is 1011 for two days in a row). I opened up the primary fermenter to add my sugar for bottling (I've done it this way before with good results), but before adding the sugar I gently stirred and got a crap...