Zanussi spin noise?

zanussi FL 1032 WM --- It started a few months ago a steady build up on spinning - a high pitched scream that tends to fade eventually or goes onto fast spin and goes completely -- there does not appear to be any other noises whilst working and is still smooth running even when screaming -- rather than start pulling apart and checking anything I can think of - perhaps a guide to possibilities would be appreciated before calling out the engineer