Broken TX Antenna!
Strictly speaking from an electronics standpoint, you should replace it with the EXACT same length. The length of the antenna is designed to create optimum output, and if you go slightly (1 or 2 inches) shorter or longer, your radiated power will be reduced, and more of the signal will be reflected back into the transmitter electronics.
You probably won't see the difference during a range check with collapsed antenna, since the collapsed antenna length will be almost identical between the two.