I am sure there is someone who can fix it, ask your parish priest if he knows it if theres a rosary group in your parish ask them. Also if your church has a Repository ask there, whoever runs it will know who they buy from and if they don’t know can likely find out for you. That’s how I’d find someone in my parish in the UK, of course you could look online too but it is often nicer to use someone found by word of mouth for something so treasured.
Also theres no such thing as bad luck. You can just keep the rosary as it is as a reminder of your grandmother. God rest her soul.
I agree, after the pandemic restrictions