Drag in feed dog

Question

My Janome 625e is about 1 year old. It has sewn beautifully until about a week ago. I have done a lot of applique work using this machine and have loved it. About a week ago the fabric started "hanging up" as I sewed. I changed the setting to more of a zigzag and it would still hang up - just sitting in one spot and creating a blob of thread. I have cleaned the bobbin casing and area by using canned air to blow out all the fuzz and/or fibers faithfully and regularly. I use the canned air regularly during all my sewing projects, to keep the feed dog and bobbin areas clean. I am at my wits end. I've read my manual cover to cover and find no solution. What am I missing?