I don't know if anyone remembers Kiwi, but I have posted a couple times about her befor.Recently, she has been sitting with her tail down slightly, but not bobbing. She seems fine otherwise, but the sitting position is just odd.
Tail Down is an unusual occurrence as Parrots normally hold their tail in a neural position between the two muscle sets that either lift or drop the tail for flight control.
A pumping action helps a Parrot with an air sack (lungs) infection as a means of pumping air in and out. A dropped tail requires the release of the upper muscles and the tightening of the lower muscle, which implies (as referred above) a possible problem with the vent region.
If your Parrot's tail does not return to a neural position, by Sunday afternoon, be at your Avian Medical Professional on Monday.