I have a 2010 Honda rancher TRX420TE A that won’t down shift it up shifts just fine with electric shift but down shifting is another story it will make a loud grinding sound like the electric shift motor is trying to work but the gears aren’t changing only down shifting! I can use the emergency shift with a Ratchet and a socket and it will upshift and downshift just fine with no grinding anybody have any ideas what it could be? Could it be the gears even though it up shifts just fine and will shift just fine using the ratchet

 

If you hadn't mentioned a "grinding sound" I would have said your downshift button is faulty, it still could be that. However I would first take the shift motor apart and check a magnet hasn't dropped off. These can act like a ratchet and make spinning one way more difficult than the other.