Serious in that you'renot extracting the moist air... remains to be seen of the solution is serious or not. Usually, if an extractor fan runs freely and doesn't make unusual sounds then the tubig into which it blows is probably bloacked. It you can find where it exits your home, the cover often gets plugged with insect nests or even a mouse nest. If that appears clear, try to trace the 'run' as far as you can for blockage. The moist air (when it was working) collects dust, skin particles, small children and other hindrances. There are special brushes with lengthy extensions that don't cost much that one can run through the tubing for cleaning.
One good idea a neighbor introduced me to was to use a good, stout shop vacuum (if you don't have one, maybe a friend does). This can be placed into the exit opening and it's amazing what you can get out of it...
Luck!