I switch the dryer on the light comes on as normal

HI. the filter is fine. Anytime you can hear a buzzing, That is behind the timer module, this will indicate that there is a serious issue concerning the timer mechanism. This device is damaged. The actual timer motor is failing. This will not allow for proper advancement of the cycle selected, in this case. The entire timer control device will need to replaced asap. Once replaced, the unit will operate correctly.