Hello John
Funny that ! well not really I was having a chat with Mr Greg about rigging and insurance .Egret II standing rigging is original 37 years old and no sign of corrosion or split wires .I have a mate who's a rigger and has done some big rigs over the years and he did Egret II s rig 37 plus years ago . I was talking about re-rigging the stick on Egret II before she came up to Lake Mac 18 months ago , and he said " If ain't broke well .....". But what he was saying was that the S/S wire twenty years ago was a lot better quality than the Chinese crape (I added the Chinese crape bit ) they produce now a days. He said to look down the turn buckle and see if there is any rust etc in the turn buckle and around the wire, as S/S wire rusts from the inside out.You should spray WD40 or such into the turn buckle once in a while to stop salt and muck .Remember also the wire is made up with more than one strand of wire so you would have to have quite a few broken strands before anything terrible would happen.
So in a nut shell just have good look at the wire going into the turn buckle and if there are broken wire strands I'd think about replacing them .I would ? and this is only my opinion , say if its your uppers I would replace both uppers and so on .The only problem you'll have is that you will have to drop the stick to do the uppers and in that case you may as well re rig the the whole stick .Lowers can be done with the stick in place.
Running rigging is basically the same Egret II has a wire halyard on her head sail and a wire winch to raise them .I'm going to replace both main and head sail halyards soon as their look and feel like barb-wire.
I know some yachties are using rope halyards instead of wire But as everybody knows Bears old fashioned.
PS Dropping your mast is a walk in the park
Cheers Bear