” it has three internal pins” Is it a french car by chance ?
Those lockers are even worse than a french car.
Speaking from a vast amount of experience it’s actually pretty hard to break a locker when taking it off, they only fit one way so if it isn’t in the corrent way it just slips off.
Very easy however to overtighten them ie with an airgun and break them.
Those 3 pin ones are the worst lockers ever. Only a a french man would come up with such a stupid design. You have all the torque needed to tighten/loosen the wheel nut being sent through three little pins !? If the wheels haven’t been off in a while and the studs are corroded in you have no chance of getting them off.
FWIW £20 to drill out all the lockers is a bargain.
I charge £30 per nut.