I've got two of these. Agree with Tony, the bolts on the hood can break off if not careful and the rope seal around the combustion chamber can fall to bits. Fire cement the ends of the burner when refitting as the seal is broken when dismantled and be careful with the filter gauze as the ends are sharp. No boiler should soot at all, if it is then there's not enough air for it and CO is being produced as well.
Gavin H
November 2008