Welcome!
That's a nice looking set. Yes, the wiring has some issues, but there isn't a source for entire harnesses, other than from another set, and the likelyhood that one would be much better is pure chance.
Usually, the existing wiring can be used with good results and this is most likely the case with yours.
It will just take a bit of work to fix the wire ends, perhaps attache a new spade terminal. I see at least one is missing.
The wires themselves rarely go bad.
It's just always a task to identify the wire colors to attach them to the right terminal. For this reason it is also not very helpful probably to provide pictures of other sets, because the colors are all deteriorated into shades of brown. However, there are examples in the forum.
Here is a presentation of the diagrams and circuit discussion:
http://www.classicrotaryphones.com/forum/index.php?topic=12347.0We also worked recently with someone else on a 653-BC set. The discussion is here:
http://www.classicrotaryphones.com/forum/index.php?topic=12334.0First step is to familiarize yourself with the components in the set and identify them in the diagrams.
Would you mind reading the date on the induction coil and any other dates, so we know the history of this set?
It looks to me like you have a very early one. The component looks like a transformer, made from iron plates, and in fact it is a transformer for audio signals. In telephony we call them induction coils. It looks like it might read as II or III 31, which would mean second or third quarter of 1931.