After driving the small TO-247 IGBTs so hard that they eventually failed, I have now upgraded the half bridge with a couple of IXGN60N60C2D1 isotop IGBT bricks. It is tuned much better now and is giving a fair amount of spark length. I will need to spend more time tuning it for maximum output, but I am getting there.
Get in here and see the latest videos on the revived little coil https://kaizerpowerelectronics.dk/tesla-coils/kaizer-drsstc-ii/