Hey Fellas, after 5 years, I decided to get a new line trimmer. Replaced my old SRM 280S with a new one. Question is, is it normal for it to be making an intermittent whirring/whining sound from the gearbox? Mainly at low RPMs. This is the same exact sound that my old one started making after 5 years, but this one is doing it already! There is gray grease in there from the factory, I checked. So, is this normal? What should I do?