Which brake are you looking for? There are two on all tubeframes. One is in the clutch assembly. The other is a small pad that contacts the drive shaft when the parking brake is applied or the brake pedal is fully depressed.
Both are available NOS. You can also buy the friction disc and bake it on in your oven for the brake in the clutch. The small pad could be relined with a piece cut from an old brake shoe.
Sonnys has both NOS. They are hard to get on the phone but they definately have them.
You could also try Ray's Mower ( check parts suppliers post for phone #'s)
Bolensman had replacement discs, he may still have some.
Here's the 1050 parts diagram. This is page 4 showing the main brake which is in the clutch assembly. Reference # 183, part # 1716618 Brake Plate Assembly (includes reference # 184, friction disc)
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