Well first remove the lever and see what is broken on it and if you can retrieve the broken off parts. Lever should be held in place by a socket head screw from the side. Remove the screw, pull the lever out and inspect it.
IIRC You have to take the end plate off on a T-Max winch to get the clutch lever off, 12 or so hex bolts. Not difficult to strip down a T-Max winch, if you haven't done it before, take a photo at each stage, it will make it much easier to put back together.