We have a cider making club and do a lot of ciders each year (100?). We're all pretty experienced but one odd thing has us all puzzled. Maybe 5-10% of the ciders each year really drag their fermenting feet. Almost all the ciders finish in 4-6 weeks but these few can go on for months sometimes, althought do eventually finish (finish= SG .995). There's nothing much we do as far as a "recipe" goes: 6 gal. apple juice from fresh unsprayed apples, 1/2 tsp. sulfite on day 1, pectic enzyme on day 3, aerate and yeast (EC-1118) on day 4. Original SG is around 1.055. Some of us have been doing this for decades. I hate to use the expression, but what could go wrong???