Cause of blowing resistors
The resistors blowing would be a symptom of a shorted capacitor. 

Film capacitors can be damaged by transients on the mains and the damage typically shows up as a short (the capacitors are made with rolled-up thin plastic film that is aluminized and a high voltage can arc through the plastic). Self-healing can take place if there is enough current to blow out the damaged shorted section but the total capacitance drops as a result. There is probably not enough current through the resistor for that to happen, which is probably just as well. 

You can try replacing the capacitors with ones with a higher voltage rating so they last longer.