Once it s inserted fully a quarter turn clockwise should lock in place the mechanism for instance one of the four feet of a car roof rack.
How to remove thule roof rack lock.
Obtain a master key.
My thule cargo box does not allow me to remove the key when the lock cylinder is in the unlock position a search lead me to a forum thread saying i have to use my key to turn the lock about 15 degrees remove the key the universal change key and then remove the lock cylinder i hope this will help some folks out there.
Twist the knob on the foot counterclockwise to loosen.
Remove the master key and try the locking key.
If you cannot find the master key that came with your thule product you can obtain one at a local thule retailer or by calling thule at 800 238 2388.
Unlock the outer housing or lockable knob at the base of the feet using the thule key that came with the set.
Turn the lock to the unlock position using the regular locking key.
Then try using the locking key.
Press your finger against the lock cylinder to keep it in place and use your other hand to pull out the master key.