You can pull that black capsule apart and you will see the cables are nothing you can replace. The 3 cable wires are permanently joined in there.
Even the name brand gyro cable sets cables are poor quality with lots of friction.
I've done over 100 gyroectomys on bso free style bikes (Next, Mongoose, etc). The bikes are built like tanks and will last forever. But the gyros are so bad on the cheap bikes no kid has the hand strength to make the brakes work, even when new. Take the gyro stuff off and run straight brake cables and the brakes work fine. Loose the pegs too. Those have the nasty habit biting me in the shins. I take bikes that are designed to hurt kids and turn them in to regular bikes to sell or give to Toys 4 Tots. If you can do a tail-whip, that's what the gyro is for but a tail whip on a heavy bike? A painful way to break your ankle bones.
The boxmart freestyle bikes are very heavy duty (except for the brakes). Kids watch the pros on ESPN's X-games and think they can do those tricks. Well the pros aren't using cheap bsos. Their bikes are $1000 + chromo bikes designed for stunts and are far lighter weight. Many of the pros are so good they don't need brakes.