Hi yantabulla. Thanks for your reply. To answer your questions,
>>> Is the hive in good condition?
Yes; it's less than a year old. Its screwed together, and although the glue I used was water-based (Aquadhere or something similar) it was painted (inside and out) first with a primer, then an undercoat, and finally with a top coat, all of which are meant to be used outside. The timber still appears to be in good condition, and the top and bottom of the boxes and lid align without much of a gap (<1mm.)
>>>Are your hives level & sloping to the front to let moisture drain out?
All slope slightly to the front, for exactly that reason.
>>>If the hive is weak have you reduced the number of supers to keep them crowded? If you have small hive beetle there they will hammer a weak hive with excess space.
I've reduced the size of the hive for winter. The bottom two boxes are still quite crowded; I added the top two boxes for summer when the population warranted them. I've never seen SHB, nor any evidence of it (smell, ruined honey.)
>>>You say brood was there. Is there evidence of a laying queen? Is the hive in trouble?
I didn't see any fresh eggs, but there are definitely freshly capped brood cells in both boxes. I didn't see a queen, but I wasn't really looking hard for her.
>>>You don't need to clean mould off frames the bees will do it if they are strong enough. Remove mouldy frames & melt them down or put them in the freezer & drop them into a strong hive in the spring.
I've put them in the freezer as a matter of course (to combat wax moth.)
>>>Sorry to answer your query with questions.
>>>Sounds like the hive is a little weak & can't maintain the excess space.
Possibly; as I said above, they're quite crowded in the two bottom boxes, and daily activity seems normal. They've still got enough honey for winter, too.
>>>Let us know how you get on.