Front forks

How do I get the bottom fork tube allen bolt out? 1200cc 78' shovelhead sportster. I've tried putting the fork spring back and putting the leg under pressure but the allen bolt just keeps spinning. Any ideas would be welcome. thx

What's a "shovelhead sportster"?

To answer your question..... Use a butterfly impact or air impact. I usuallu use a 3/8 butterfly and it works every time. Pulling down on the slider will help put pressure on the bolt sometimes and help it come out.