Probably dragging of the cable in the protective covering. I'd first check the cable to ensure all bends in it are gradual (like less than 45 degrees). Some cables can be removed from the protective sheath, cleaned and regreased. Not sure which would work best white lithium for graphite - there is a Teflon cable/chain grease used on motorcycles. Even Liquid Wrench would clean it up and lubricate it. Check also where it goes thru the left front wheel bearing cap to ensure it has the C-clip or cotter pin present.