Judy
Presumably your feeder sits immediately over one of the holes in the crown-board sitting above the brood box – or is it above a super? Unusual for bees to block a feeder entrance / funnel with brace comb. Sounds as if they have run out of space in the hive or don’t like the hole in their roof – too much ventilation?
Cutting out the brace comb with a sharp knife and melting off the wax residue with hot water sounds good. I would worry that boiling water would damage the plastic. Any remaining propolis can removed with a soda crystal solution / kitchen scourer.
Bees will take down several pints of 2:1 sugar syrup in a day if they really need it. Any left after a couple of days will naturally start to crystalise – especially if the sugar in the original mix was not totally dissolved and subsequently seeds the solution.
Douglas