How can i fix my beko DRVS 62 W?

Hi my tumble dryer has just started acting up with the clean filter light coming on ive done all the cleaning out with hoover and unscrewing the sensor in the drum and cleaning that and ive done the hold the buzzer button and the test program all works fine but when doing the test the clean filter light is very faintly flashing on each setting and i cant find anything to tell me what this means can anyone give me a deffinate fix ie would it be the main program board at fault or the sensor thermostat at fault? Thanks in advance hope someone can help me fix this asap :-)