Welcome to the NAWCC message board.
Your clock sounds like a 400 day, also known as an Anniversary, clock. The steel thread you mention is the suspension spring.
There is an entire message board forum on 400 day clocks about 3/4 of the way down the main MB page. If you post your question there, the real experts on these clocks will be there to help you.
These clocks can be very frustrating to set up properly after the suspension spring has been replaced, so have patience and ask all the questions you want and/or need to on the 400 day clock forum.
I am not at my shop, so I don't have the address of the Horolavor Company, the makers of the suspension spring you need, but someone on the forum will look it up for you.
You will need to post a photo of the back plate of the clock with the suspension spring guard (if your clock has one) removed. All technical info on these clocks comes from the arrangement of the back plate. The first posting on the "Clocks" forum has instruction for posting photos.
Have fun working on your clock!