Not sure on which specific string to get but any replacement wire for tumbi will do..to rewire it get one end of the wire and loop it round the bottom end of the tumbi where the main wood stick comes out the bottom of the round bit (there should be a groove there ) then twist the remaining end bit of the wire round and make sure its tight and won't come off the bottom. Then on the other side pull the wire straight over the bridge to the tuning bit, there should be a hole then pu the wire though the hole and leave a bit hanging out. Then bend the bit hanging round, then wrap the slack wire round the bent bit so that it won't come untangled. Then to tune twist the round bit which the wire is wrapped round