IT IS ILLEGAL TO DISTIL YOUR OWN SPIRIT ANYWHERE IN AUSTRALIA AND WE AT TAS HOME BREWING DON'T CONDONE THE BREAKING OF THE LAW IN ANY WAY WHATSOEVER.

In our vast experience...

Click on the symptom...

Wash not reaching 990:  Not enough water or too much sugar or poor temperature control.  These are 'racehorse' yeasts and need to be treated properly to finish the 'race'.  It is important not to exceed the ratios of sugar:water - only use 8 kg of sugar or 9 kg  of dextrose per 25L.  Make sure you fill the barrel after a couple of days.  Keep the brew at 26 degrees C.  Remedy:  Add a stuck yeast.

Wash not clearing:  Incomplete ferment (see above) or too hot for clearing.  Convection currents in the brew keep the sediment swirling.  Remedy: cooling the barrel will drop the sediment faster (Stokes's Law).

Wash bubbles over:  Fermenter too full to start, top up gradually after a couple of days.  Or a bacterial infection and a yeast ferment.  The latter occurs because of dirty equipment and the high nutrient, high sugar solution is excellent for bacteria, too.  Bleach everything.

Wash is thick:  Caused by a bacterial infection and occurs because of dirty equipment; the high nutrient, high sugar solution is excellent for these bacteria.  Toss the brew, bleach everything and start again.

Wash takes too long  When using the 24 hour or 48 hour yeasts we are feeding them more than what the packet says.  Of course they are going to take longer - 5-7 days at 26 degrees C (longer if it is colder)
 

Distillate not 90+%  Distilling past 76-78 degrees C.  Remedy: turn the cooling water up.  Using an incomplete wash (see above) excess sugar is a waste of money and mucks up the temperatures in the still and drops your finishing yield.