Some picking hints (only to be used when appropriate!)

- get a couple of tools
- a straight thin metal strip as long as the key is, about 1/3 as wide, and a little thinner - used to rake the tumblers by sliding in and out
- another tool to fit in the other side of the lock with a bend in it - used to slightly turn the lock towards the unlocked position

- the theory
- there are multiple pins that need to be in a precise position for the lock to turn, and only the key gets them all in the right spot at the same time
- however, due to manufacturing tolerances, wear, variability, etc when you turn the lock only one or two will actually engage and hold the lock closed
- when holding the lock closed they have friction - if you press that single tumbler down it will tend to click into its proper position and then be held open by the lock as it turns slightly to where the next tumbler catches it
- this allows you to release the tumblers one by one until they are all open, at which the lock just rolls open

- the practice
- use the right angled tool to GENTLY rotate the lock towards the unlocked position
- use the other tool by raking it in and out over the tumblers
- if you are making progress you will feel the tumblers clicking into position and the lock making tiny movements toward opening
- with any luck after 5 or 10 rakes the lock will release and open
- with bad luck you might fidget with it for an hour before giving up in disgust

The door keys from my old '63 Volvo 122 fit the ignition of my Uncle's 60-ish Land Rover. I forget how we discovered that. But there really aren't that many variations on the keys, especially on older locks with fewer tumblers.