How much better does this look! Core Lock Services replaced the window locks on a house in Mt Kuring Gai (just north of Hornsby) during the week. We also changed the key on all other door locks so that every single lock, including the window locks are on ONE key. We can do the same for you too. If you need a local locksmith to North Sydney, we can help. Call Core Lock Services on 0423 442 298 to arrange a survey or quote.