Flamegun weedkiller - Sheen X300

Hello,

I've acquired a used Sheen Flamegun, model X300 for 20 pounds at a car
boot.
No instructions of course, hence my posting.

Firstly,
How to Start it.
Here's my guess, please correct as needed.

1. Ensure vavle closed
2. 3/4 tank of paraffin
3. Heat the end near the coiled pipe on a gas barbecue (how hot, how
long, necessary ?).
4. Pump up pressure to 3/4 scale, that's a guess (scale is 0-60 psi).
5. Open valve fully and ignite.
6. Adjust valve for best flame.

Any other tips on maintaining and using this device.

After Googling, I see they are still available at 150 pounds. Little
information on using though. Somebody was selling instructions.

Thanks in advance.

Jim