Fix the number of lock pins to about 7, set the strength not only for the lock pick but also for the lock, determine the probability that the lock pick will break based on the difference, and change the event of the lock pick breaking from after the lock pin pops up to just before it pops up, and do not pop up if the lock pick breaks.
After doing this, if it can set the strength of each and minimum and maximum probability of lockpick breaking, you should be able to balance various things, such as making it impossible to open a high-level lock with a lower lockpick, using a higher-level lockpick to open a lower lock without breaking it, or conversely, making it so that no matter how good the lockpick is, it will break at some point.