Transfer bars, or lifter and striker as they are called by H&R, are not well made, they have a habit of breaking occasionally, I keep a spare just in case, but have never had one break.....yet! And yes, it's loose in the frame, but it should move up and down with trigger movement, but should stay withing it's range of movement unless it comes loose on one side which is what happens sometimes, can be peened back into working order sometimes.
Tim