What did the trick?
The wooden spoon I forgot to mention for the gentle tapping?

Another trick for looking after PBs;-
If you've washed one and want to get it dry, put a rolled-up "wick" of kitchen roll into it and leave it to sit, preferrably safely propped upside down.
(I normally give a final rinse with a little distilled water, but I keep that in the house anyway, I have carniverous plants that need it.)
Any water inside that evapourates will go to the kitchen roll because it's absorbent.
A distilled water final rinse will get rid of any water that does contain anything to leave as a deposit.
Just tear the kitchen roll into a width that will go into the hole easily after rolling it up a bit.
