How do you know the hopper leaks? Keep in the mind it can only seal under vacuum, if noted slight smoke during shut down that’s not exactly a leak. If you open any lids make sure bump them while under vacuum to reseat the seals. One thing Ive noted in the picture is the lid looks like it is not sitting flat. Is that just the picture? On the hinge side you can level the lid to sit flat, I have to wonder if it got bumped in shipping. You can loosen the hinges mnt where its bolted to the hopper and then put some wieght or simply use the blower to pull a vacuum on it and retighten the bolts. That may be all you need to correct the leak. The lid leaking really is not that big of an issue unless its excessive. Other leaks however can be a problem.
Aha if you had a good flash back, you now know the power of this gas. Im assuming you may have lit too early? This is do to where our lighting port is, its up higher so you have to wait a good bit for the combustion to migrate down, otherwise the air jets will introduce air below it and that causes air mixture into the gas.
For your filter media just use your fuel that you are using. Start out in small increments, Its more important for the machine to be able to breath then it is to have filter media in here. This filter is for ash/char debris and thats really all you need in there.
It looks like you are ready to engine run. Run the gen on gas leave it disconnected for now and run. Get to know it a bit and listen to it run and how stable it is. You can play with mixer controller here as well. the top switch arms it and the lower switch is to go from manual mode to auto mode. “Off” its in manual mode and “ON” its in auto mode.
Turn off the gas supply valve and let it run out of gas and then once you have the machine flaring off again you will be ready to perform an engine run. First is you turn off the blower and shut of the flare valve. Open the gas out valve and then arm the mixer in manual mode and turn the mixer pot knob fully CCW “valve is fully closed” hit the starter and watch the 02 guage once it goes in the rich condition direction, then begin opening the valve slowly, You will be able to see this effect the 02 reading. Slowly open the valve until she fires, once it fires you may then need back off the valve slightly but let is get going and then fine tune. Once its up and going slowly make adjustments and try to get the readout between 14 an 16 on the gauge and then put it auto.
Now watch the automation on the machine and note whats going on, The hopper may vibrate the engine crashes for example, You will have to play with the automation a bit to fine tune.
Keep us posted everything looks awesome