I have a komatsu D39 with 3 gears run by an up and down button on the left lever. It shifts up no problem but won't down shift, with it being around 10 years old i figured the buttons were worn out or corroded so I bought a new one and replaced it with no luck. I haven't really gotten a chance to get into it but i figured id see if anyone had a thought or similar experience with this issue. any hints would be great thanks.
if you lift up the boot on the bottom on the directional lever you will see the harness have a close look around the cork screw looking thing and also have a look at the harness and move the lever, some times the harness can catch the block and tear the harness.