The pilot said he was landing on runway 07 with a 5-knot right crosswind. He said that shortly after touchdown, the aircraft started a slight drift to the right. The pilot said he applied left rudder to compensate and felt a "thunk" as the left rudder pedal locked forward, over center, underneath the brake pedal, which prevented the use of the left brake. The aircraft briefly lurched to the left. He applied hard right rudder, but with no apparent effect. He next applied right brake and intentionally ground looped the aircraft to prevent going down an embankment on the south side of the runway. The airplane's left main landing gear collapsed, followed by the left wing, left aileron, and forward fuselage being wrinkled and bent. The pilot said that the rudder/brake pedal assembly has only one master cylinder for the braking system and it is located on the right hand side. He said there is a mechanical linkage from the right to the left, which is prone to jamming in certain rudder pedal deflections. He said that other pilot's have reported this problem with their amateur-built airplanes manufactured from the same kit.