If the rod sticks, and you brake off the flux at the end, you need to burn it back to the flux before it will work properly again.
What you do is get some scrap plate, connect it to the earth clamp, and drag the rod along it at about 45 degrees really fast. Continue to do this until it is back to the flux.
And yeah, those welds are pretty bad. Don't trust them for anything. Do more practice before welding kart pieces together.