The springs on your clip pedals are put under enormous strain every time you are slamming down the gate, add to that the number of times you clip in and out of your pedals in a session and it's no surprise that these small springs can fail over time.
Luckily these are an inexpensive part of the HT pedal to replace and this kit is comprised of the X2 springs which have more tension than the standard T1/T2 springs, but are the replacement for the SX versions of these pedals. They are the standard spring found on the X2 and X3 pedals.