bosch classix 1400 express (noisy drain fan)??

i have a bosch classix 1400 express that runs a cycle until its time to drain. when the drain pump starts its little fan makes a massive noise like something is stuck? i have had the front off only to get stuck on not knowing how to get the glass door rubber off. its definately the drain pump fan making the noise and if i have to swap for new then i will but how do i get to it properly. has anyone else had this trouble?