Definitely DO NOT put a 20A fuse in there!!! First thing I'd do is reach up into the fan exhaust and make sure the fans rotate freely with no wobble. There is probably a problem with your fans and one or both may need to be replaced. You may want to search fan replacement. I believe someone on here had some wiring melt???
Found the thread. Post #9.
http://986forum.com/forums/general-discussions/29567-electical-burning-smell.html