* I requeened my 3 year old hive 3 weeks ago
* But, I couldn't find her,
* a good brood pattern.
* but there was not a lot of capped brood.
You have good queen there and it is not necessary to find her. Some queen run away and hidden.
A lot of my comb is very dark from several years of use,
When you put more boxes to the hive, lift those dark frames upp for honey. Bees eate pollen away and when bees hatch from cells thay fill them with honey. When you extract honey you can take away old frames.
Give them foundations to build 2 box during summer that brood frames are new for next season and for autumn.
Should I break down the old hive again, or should I wait longer so as not to keep disrupting it? I didn't see any queen cells. If the queen didn't make it would they have started rearing a new one by now? I'm not sure how to proceed at this point.
If you have made hive queenless, it should be queen cells there. It takes 2 days to find queen cells. And when cells are capped, it is very easy to give a new queen. It may be that they have raised a new queen and there is unmated queen in the hive?
But you can do a nuc and you put the new queen there first =
1) Take a frame where it is hathing new bees and shake every bee away from frame.
2) Put the nuc over the big hive to it's warm. Put double screen between nuc and big hive. Give the queen to nuc and shut the opening for 3 days.
This is 100% sure to keep queen alive. After this procedure nuc and main hive will have same odour. When you find the "ghoast " queen , you just kill it and put bees together.
If the main hive has unmated queen, sooner or later there will be brood.
It is also possible that young queen hatches and it will destroy during it's flight. Or youg queen have some problems and it dies when it try to go out.
If hive has no brood and no queen, it is very nervous. They ventilate and many bees have they odor gland open. If you give odor of new queen to queenless hive, they rush toewars to odour and start to ventilate happily. It may be also hostile bees thre and they attach the new queen.
If the hive has no larva, it is easy to test do they have queen. Just give them frame with young larva and soon they build queen cells. It they do not build queen cells, thaen they have some kind of queen there.
Somethimes bees have very violated queen there which cannot lay eggs. It is difficult to find her.
And finally. If you put old hive 2 meter away and a new hive in the old place, old bees fly there. It will be quite a mesh when they seek brood or queen there. So you see, which part is queenless. If you have unmated queen, it can fly to old place, and the old hive will be nervous.
I do not know, does this help. But when you get the new queen, it is usefull to give her a hive. The hatching frame is sure to use.