how can i fix my fan?

my air cooler, LOGIK model No. HLF-20R, has an ongoing problem whereby you are able to hear the motor turning (at a very slow speed though) but it isnt powerful enough to turn the fan blades. sometimes it needs a little help by assisting it to turn until it builds up enough momentum to turn on its own and at other times it just refuses to turn at all. i do suspect that the motor is probably jamming or slowing down due to dust build up, however even after cleaning it out via means of an air line compressor it doesnt help. the machine is just over a year old. please advise asap. thank u