dont forget, dudes and dueettes, that there has been a circuitboard revision for the P38 fairly recently, and we might be dealing with an improper dip switch setting as well (these new settings are different than previous ones).
Since you do in fact have an outside air kit, is it at all possible your inexperienced installer didnt remove the insulation disc in the intake of the passthru?
Also, I dont agree that the door should be left open after lighting....light it, close the door. if you have to puit it in test mode once or twice, do so....I outlined this procedure earlier. Other than the alcohol thing, his procedure is quite good and sound. I dont like using straight alcohol due to the flammability aspect....the available gels usually are somewhat retarded so they dont flare up as much.......alcohol is very flammable, and could result in fire issues if used not carefully......
As i said earlier, there could actually be a bad part in the unit, and it would be REALLY NICE to see a draft reading on this thing.......again, your dealer should have done this upon install......not that it helps, and I feel your pain, but the dealer is at least half of the stove-buying equation. They should be willing to check this thing out....even thought the P38 is non-autoigniting, it should be light-able. Usually the lighting issues with these things are the customer doing something wrong (tho im sure likely not in your case)....we had a customer using very little gel in one......they'd go to light it and the gel would burn out before the unit could get up to temperature, so, it wouldnt feed or stay lit.
Also, dont forget to close the front door, the ash door, and the hopper lid....the p38 WILL NOT feed with any one of the above open.
In answer to your question about how to articulate these issues to te "repairman", I would insist on a draft test, see what the readings are, and go from there. The circuitboard might be at fault, so, he ought to bring another with him (any dealer worth their salt keeps extra anyhow). The vac switch RARELY fails.....VERY rarely..........ever so rarely (Im saying here its probs not your issue).....
let us know! We'll get this figured out.