Hello I’m new here but I have about 4 HD25 2 of them are my personal collection if you have some type of outboard stand use it remove top plug for air to drain remove lower plug and it should drain out to refill what I’ve done is get a gear lube bottle with a small nozzle get a marine grade gear case lube put the nozzle into the drain port and squeez tell you see oil come to the top plug When you see that happening you will want to turn your motor to where you can have both plugs facing up plug the top hole with your finger or the screw and close off the bottom port