wayne
clensan will do the job
we have sprayed without extraction but that was a light spray and wouldn't have any effect on the milk smell.
i wouldn't bother cleaning if it don't need it, just spray on clensan, agitate in, then leave for 10 or 20 mins, then extract with high psi. 350 400 will do. should be fine, did one today but needed cleaning as well, all though in clensans defence, it got quite a few stains out even before we powerburstedededed