If you examine the pins on a male stage pin connector closely you will see they are not solid. Instead they are two sections with a slight gap right down the center of the pin. In order for the male connector to stay securely connected to the female, the gap in the pins must be properly maintained. Over time the halves of the pin get squeezed together. You will notice that the male end loosely falls out of the female socket, this is a sign that the gap must be reset. A pin splitter is the tool used to fix this problem. It is "T" shaped with a handle at the top. At the bottom of the T is a hole for you to slide the connector into one pin at a time. Inside that hole is a thin blade which you slide between the two halves of the pin to properly adjust the gap. Pin splitters are a standard tool that should be used as part of a yearly maintenance routine. Pin splitters are also a handy thing to have in your pocket during a light hang. Don't tape the two connectors together, get a pin splitter and fix the problem. They can be purchased from any theater supplier for around $25.
The original Pin Splitter was made of steel and very heavy. The Pin Splitter II is made of polycarbonate and much improved.
The Ultimate Focus Tool also incorporates a device for splitting pins.