The brake bands will only come out with the steering clutches removed. Assuming you've got to covers off, your going to have to take out the two rings of bolts that hold the clutches to the drive flange on the inside, and the driven flange on the outside. As Dozerbill said, the way to do this is to take out as many bolts as you can, and then use a jack to push on the track to make the machine move forward, or backwards (the direction doesn't matter, but backwards can be easier if the blade is down and digging in). It doesn't take but a few strokes on a jack to get it moved enough to get out another set of bolts. Usually you'll get 3 or 4 at a time on each side. I'd have to check a parts book, but if I remember right there are about 18 per ring.
Once you get all but the last one out, you need to hook up the brake band. What I usually do is rig short chain in such a way that it pulls the ends of the band together as you pick up on everything. Once you get it hooked up, remove the last bolt. Both sides of the assembly ride on a locating lip, so you'll need to, use a pry bar to slide the brake band/steering clutch assembly together, to break everything loose.
Once everything is hanging free, you can begin to lift it out. Once you clear the main housing, you'll notice the brake drum is open on one end (toward the middle of the machine), and closed on the other side. Be really careful as the clutch pack will slide out of the drum if your not careful. Usually what I do is put a big C-clamp from one side to another to keep the whole assembly together. If it falls apart, you take the chance of bending the drivers on the clutch discs, and you don't want that to happen.
Once you get it apart, take the brake band off. While your this far, you'd be wise to take the steering clutch assembly out of the drum, and check the stack height on the discs to insure they are within specs. It's a long way back in if your at the low end and plan to keep the machine, and use it, for any length of time.
If the clutches are worn, you'll need to get someone who has a press, and knows what they are doing, to rebuild it for you. It's not all that hard, but the parts are heavy, and they have to be right or you'll 'lose your religion' in short order.
Once you get everything squared away and ready to go back together, just reverse the procedures for taking it out, to put it back in. One thing, insure ALL of the bolts are started before you begin tightening any of them. This means more jacking, and at least two full rounds to accomplish, but if you try tightening them as you go, you will have several that won't thread in and you'll be backing up and wishing you had started them all first.
For parts, give Offroad Equipment a call. If you've got a way to rivet the linings, they can often provide just those, or if you don't, you can buy the whole band assembly with the lining already on it. Regardless of which route you chose, I've used them quite a few times, and they are about the cheapest I have found for parts. In fact I did the same job your looking at, for a customer, about two years ago. In that case they had to have everything, both brake bands, both steering clutches rebuilt, along with various other repairs.
If you run into any issues, post back, and me, or someone else will be glad to help. If you need to talk about it, rather than doing it all in writing, my email is open, and I'll be glad to give you my number.
Good luck, Wayne
Offroad Equipmet Parts