I'm with miki, I have never had an after market work. Did you have a full 12 volts when you tested that starter? Did you have a very solid ground? If so, then your bendix could be at fault, or it could easily be poor contact with the brushes, from slush on the armature due to water ingestion. Amazingly OME brush kits are cheap, also check your magnets, of course if they are broken you will find their bits and pieces in the starter.