All companies are making everything cheaper and at the lowest tolerance. Just put some higher wattage resistors in the units you have on service and be done with it. Each manufacturer I work on seems to have at least one weak link. A 10cent resistor ain't too bad. Also, I think it's 3 months warranty/free service? Used to be 6 months and/or a year? What about Kone and their POS PCB's that cost 2K+ to replace?