1. How tight are your scrubbers? You say you pack them in there tight but able to breathe through easily. Try not packing them in next time. You may be causing your column to flood. The steam can get up but the fluid can't get back down. Maybe try putting them in fairly loose next time.
2. How much are you putting in your boiler? I wouldn't go over two thirds full (personal preference, others may argue). Otherwise your column will again flood due to you actually pushing your wash up the column.
3. Do you have some sort of cooling condensor other than in the fluid discharge for refluxing? May sound like a silly question but needs to be asked.
4. I've found that your wash should be at a constant slow (I emphasise SLOW) boil for you to get any steam up the column.
5. Has your wash properly fermented or do you just have a sugar solution in your still? Are you sure that the fermentation went to plan? Bubbles, froth, heat, SG checks, etc.
6. Gas should be fairly easy to use. Put it on full until your wash starts to boil and then back it off to it's lowest simmer. You may be able to up the heat later on as you get a feel for your still.
7. What alcohol content is the fluid coming out as product?
From personnal experience, number 1 or 2 sounds like the problem. I had the same trouble when I started. I'd pack the damn things in there until I couldn't get any more in and find I could still breathe ok through it too. I'd also overfill the boiler and get milky product out of the condensor.
"Forgive me father for I have sinned...."