Thought as such!
TB, is that really how much that PU tube drains that pot? FARK!
How? Is it cut on the angle to be flat against the bottom?
Cut at an angle so it sits more or less flat on the bottom - that particular brew I did a little bit of tilting to get the last of the liquid out... had a smidgeon of goo in it but i was short on volume. Normally I'd be leaving behind something like 500ml of wort, perhaps 1mm deep accross the pot bottom.
Remember - the spinning itself does bugger all because while you are spinning, you're just stirring all the crap up into suspension - it all happens while the spin slows down, as a result of the frictional forces between the sides and bottom of the pot and the liquid.
Tall thin whirlpools dont have the optimum shape for the currents that do "the job" in a whirlpool - wider flatter ones have a much better geometry. Ideally, the shape of the body of wort will be about square.. as wide as it is deep. Its not quite that, but near enough.
Also - the same amount of solids will form (surprise surprise) the same sized pile of gudge no matter what sized pot you put them in. 25L of wort (A) will make the same pile of goo in a 27L pot as it will in a 75L pot... its just that the pile will go all the way to the edge, or if there isn't enough room, just make a layer. In the bigger pot it sits in the middle with clear space around it. Same amount of malt to make a concentrated wort in a small pot??? same amount of solids, same sized pile of goo, but an even smaller pot and a worse result.
A lot of whirlpool success is also about the technique you use in draining. You should start slowly and gently, dont smash up the cone with the currents you make draining wort away. Once things are going, you can gently increase the rate, the cone has had a bit more chance to settle and stick to itself and you aren't making sudden changes in the amount of pysical stress its under - just monitor the wort to see that it stays clear - and then its vital that you slow down as soon as the top of the cone gets to the surface of the wort. You must allow the level of retained liquid in the cone, to drop at the same rate as the liquid level in the pot - if the liquid level in the pot drops faster than the cone can drain, it will be heavy and slushy and it will just start to flow and pull itself apart.
Decent pot - good boil geometry is close enough to good whirlpool geometry, so its a win win. But a bit wider is probably better in terms of whirlpooling.
Correct amount of kettle finings - and IMO Brewbrite is the best on offer
Good technique and a willingness to be a little patient.
Blessings of the gods - because sometimes it just doesn't bloody work no matter what you do (short of buying a new pot)