78 - Steering Column disassembly

I have a horn problem and by all tests it appears the problem is in the steering column, I've disassembled the column to the point where I'm at the Lock Plate which is in front of the lower cancelling cam/horn contact. My question is how do I remove this Lock Plate? Everything up to this point seemed straight forward. Since I'm down to the turn signal/ignition area I don't want to screw anything up. It appears there might be a locking washer, but it doesn't seem to move (you can see my screw driver scratches). Has anyone done this before and make suggestions before I move any further?

   There is a spring behind the lock plate and a special tool is required that presses down the lock plate allowing you to remove the snap ring in the groove on the steering shaft. Then you can remove the lock plate. A factory service manual is an invaluable resource when doing jobs like this.

Thanks, I figured it would be something like that. It's probably going to be fun finding the tool. I'll try a couple of shops around here that work on Vette's maybe they'll loan it to me. Thanks!

   It's a fairly common tool since most GM cars of that era required it. I think I got mine from JC Whitney a long time ago.

Thanks 73Shark, I goggled it and it's all over the place. Thanks again for your help.