My brother was riding his trike around a corner and the rear end siezed up and broke some welds. We looked at it and the secondary sprocket had come loose and moved sideways. That caused the small chain to bind so when he tried to pedal it put stress on the brake drum and broke it.
I took some pictures into the Berkeley Rad store and they gave him a replacement brake assembly under warranty. Hopefully we can keep the sprocket from coming loose again with some blue locktite.