Oh, this is realy good! I was hopeing you have this design. You can easyaly convert this FEMA style gasifier in a lmbert.
If you need to run a engine, things might get tricky. But to make clean, burnable gas, your gasifier can easyaly be repaired in a hour worth of work.
First, you need to manufacture a lid to close the firetube top, the place where you now put wood and draw in air. It needs to be air tight! and easy openable, to add in new fuel.
Then, you need air nozzles. You need to get air in a exactly right part of the firetube. This part is located about 15cm from the bottom of the firretube. I wuld go with 3 10mm nozzles.
And last, you need to insert a steel ring in the firetube, outside diameter 10cm (firetube radius), iner diameter about 5 cm.
Thats it. Fill with fine charcoal up to air nozzles, start the fan, light, ad wood pelets and you WILL have burnable gas in 60s.