new toilet flushes but residue still remains?

Residue staying in the pan is either not enough water to flush or a restriction either in the pan outlet or in the pipework there after. Only thing to do is demount everything and look more closely. Sewer gas smell only comes from pipe leaks or depeleted seals. It could be also from someone who suffers from large stools that have blocked the pan bend on cheaper models that are smaller in diameter than the UK types.

Maximo
July 2008