Sounds like the motor brushes have worn down.Take the brushes out of the motor for inspection.10mm or less of carbon on them and you will need to replace them. Genuine beko brush part#371202402 available at www.espares.co.uk brush set £7.49 Check as to which motor and drum is fitted to your 5140s because some 1400 silent spin models were fitted with stator and are brushless.If yours is the latter,check the wiring to the motor,make sure the tacho on the motor isn't loose.Check the wiring on the tacho,and check the drum sensor and the two wires attached to it.
paul
January 2012