The Von Duprin 050500 88 Rim Latch Tail Kit is used on the 88EO, 88DT, 88NL, 88L, 88K and 88TP devices. The kit includes one Latch Tail, two Latch Tail Springs, and two Latch Tail Pins. The 050500 does wear out over time due to the 88 Rim Master Cam and the 88NL Cylinder Cam, 88TP Cylinder Cam, or 88K/L Cylinder Cam sliding over them. You may notice that they are usually covered in grease, this is usually applied at the factory. The Latch Tail Springs push the Latch Tail and extend the Latch Bolt. People are quick to change this piece if there Latch Bolt is not extending, which may be the issue, but could be something else.
Before I would change the Von Duprin 050500 88 Rim Latch Tail Kit I would check the Cross Bar, and make sure the Set Screws are tight. The Set Screws are located under the Cross Bar and push up on a wedge which expands a Ring (Wedge Ring). The Cross Bar should always be parallel to the face of the door, you should never be able to twist the bar. The reason this is important is that the Cross Bar is heavy, and all of the lifting of the Cross Bar is done by the Hinge Case Spring, which is located in the Housing over on the Hinge Side of the door. The springs in the Von Duprin 050500 Rim Latch Tail Kit DO NOT provide any lift for the Cross Bar.
The Von Duprin 050500 88 Rim Latch Tail Kit is located inside the Center Case Housing, and is easily accessible by removing the Center Case from the door and removing the 4 Phillips Head Screws on the back cover plate. After that it is as simple as putting the Von Duprin 050500 88 Rim Latch Tail Kit in place and with the same orientation as the old one. You might want to add some grease or white lithium to the new parts also.

This is the Von Duprin 050500 88 Rim Latch Tail Kit