A truck's parking brakes will not release completely. Technician A says this could be caused by a restricted air line to the spring brake chambers. Technician B says a damaged spring brake control valve could be the cause. Who is right?

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Both A and B. Both technicians are correct. Parking brakes in air brake systems are released by air pressure. Either a restricted air line preventing full air pressure from reaching the spring brake chambers or a damaged control valve that doesn't allow proper air flow could prevent complete release of the parking brakes.

A truck's parking brakes will not release completely. Technician A says this could be caused by a restricted air line to the spring brake chambers. Technician B says a damaged spring brake control valve could be the cause. Who is right?

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