I used / disassembled many T/C locks for several years...here's how I did it:
Here's how I do it:
1) Remove the lock from the stock;
2) Place the hammer full forward in it's relaxed position to relax the mainspring and rotate it's tumbler notch away from the guide rod as far as possible.
3) Remove the mainspring & guide rod...I just rest the lock on a piece of carpet and use needle nose pliers to push the end of the rod out of the tumbler notch.
WEAR A HEAVY LEATHER GLOVE ON THE HAND HOLDING THE LOCK IN CASE THE NEEDLE NOSE PLIARS SLIP;
ENCLOSE YOUR WORK AREA AS BEST YOU CAN IN CASE THE SPRING GETS AWAY FROM YOU!
4) Remove the bridle plate & screws
5) Remove the sear / sear spring / sear spring plunger
DON’T LOSE THE FLY
6) Flip the lock over and support it across two pieces of wood or something so the tumbler hangs free;
7) Remove the hammer screw;
NOTE: The Hammer slides onto the "tumbler" shaft...you may be lucky, and after removing the hammer screw, you might be able to wiggle the hammer off the end of the shaft if it has any play at all...usually you cannot.
CAUTION...DO NOT THINK YOU CAN SLIDE A SCREWDRIVER BLADE UNDER THE EDGE OF THE HAMMER AND PRY IT OFF...YOU WILL MAR THE SIDE PLATE, AND WORSE, YOU MAY SNAP THE TUMBLER SHAFT OFF.
8) Take a punch as large as the end of the tumbler shaft, and gently tap the tumbler down through the hammer;
Reassemble in reverse order;
REMEMBER TO PUT THE FLY BACK IN THE SAME PLACE