John@ToolInspector

I would say it sounds like the gears not the brushes because as you rightly say that would affect both forwards and backwards. Is it making any unusual sounds or smells? I would cut my losses from the discount you got and take it back because even if you do find the problem and fix it you will lose your warranty because you have taken it apart. If 6 months down the line something else fails you will lose out big time. It's just not worth the risk. John Tool Inspector