Steering wheel vertical tilt lever / arm.

You lower the arm to tilt the steering wheel. After adjusting the vertical height of the steering wheel, you raise the lever back to the top-most position and the steering wheel locks in place. Recently, I had to change the ignition lock (where you insert the key to start it) and falsely assumed I'd have to remove this arm to lower the whole steering column to get to the lock (i had to drill out some rivets...). I replaced this arm in (as far as I can tell) the exact same way that I removed it, however, it will no longer lock in place and the steering wheel keeps lowering its self while I'm driving and even with the arm in the upright position, i can lower the steering manually with one finger and very little effort.

How can I fix this and make it (and the steering wheel) STAY up top in the highest raised position??