Repair / Recreate default machine

I have a Mac running latest OSX / latest Docker. The docker-machine named default was working OK but after trying to adjust the network settings I have broken it - at least one NIC is no longer usable (it stopped supporting IPV4 and DHCP). I tried to see if there was a quick way to use VBoxManage to reinitialise a network interface, but there are too many options for my current skill level.
I tried a different tack.

docker-machine create -d virtual-box tst
then in VirtualBox, I added a third NIC and set it to bridged mode
finally took that NIC’s MAC address and updated my DHCP reservation - all set up as I wanted, but my containers are still on docker-machine default.

Is there a command to revert a docker machine config to default values without losing the containers?

Steve

If the Docker machine has broken the containers running on the container are most likely not running to full configuration, Stop the containers, delete the docker machine and recreate a new Docker Machine.