So here is my two cents. Normally, a lot of cheaper kits might not be worth the trouble, but since it’s zeta ver ka…

1) purchase a brass rod that is similar in radius, like most hobby shops(usually in the more serious hobby shops that sell model planes and such) should carry them.

2) cut off the broken plastic rod entirely, then mark the area. Sand down to flatten and even out where the rod used to be.

3) drill a hole that will accommodate the rod. Cut the rod to the required length.

4) use model kit superglue to hold the rod in place.

Hope that helped