Filament Loads But Won't Unload

I'm running Mode 3, but for some reason, T1 won't unload. It will load okay, but when I try to back it out, you can hear the motor working but nothing happens. Even trying to pull on the filament while its supposed to be unloading isn't helping it to come out. I've fed more than enough "clean" filament through to make sure that I cleared the whole tube of what seemed to be jammed. Didn't seem to matter, still won't back out.

Any idea's on what to do? This is my first time working the multi-color print after getting this thing all set up. But I went through a ton of setup and what not and never had this problem with T1 until I just went to go do this print. Sometimes it grinds while it won't move, other times its just silently not moving.

UPDATE

I cut the filament and pulled it through, then reloaded the filament. I pushed it all the way through to the extruder, then backed it out. It moved maybe a centimeter before it stopped. When I pushed on it a little, it started moving again and finally backed out. But its not going to work if it requires assistance.

UPDATE #2

I removed the stepper motor that feeds the filament to make sure the grub screw was tightened as suggested. The "top" gear that feeds T0 and T3 wasn't even on the stepper motor and was sitting inside the sliding plastic parts. I put the gear back on and tightened. Oddly though, it's been the T1 that won't feed or retract correctly.