I thank it is the old grease that they used in the motor. I have three of those FW and ever case smelled when I got it and I put a bowl of coffee grounds, maybe 4 tablespoons each time in the closed case. Changed 2or3 times in 2 weeks and odor was gone. I new this because I had been on vacation one time and ref. went out smelled terible had it fixed under warranty and like to have not found anything to get rid of the odor but coffee grounds new out of can worked.