I have a three-way switch where I would see a spark behind the switch every time I tapped it, so I wanted to replace the switch. Upon replacing the switch and wiring it all up as before, I now get a short (circuit breaker trips) whenever the switch is in the "on" position. If I take the switch out and connect the "hot" wire to one of the two travelers (or leave the 3-way in question off), the other 3-way switch in the circuit, and the light that they control works fine, but if I connect the "hot" to the other traveler, the breaker trips instantly.

Here's a diagram of the wiring in the box. I've only investigated this box; not the one housing the other 3-way switch, so that's not included. S1 is the switch in question; I don't believe S2 is related, but it's also in the box and shares some wires so I've included it. Circles represent where wires are coming into the box; squares are switches; and triangles are pigtails. Finally, both switches are grounded through the box; there are no ground wires in this diagram. Forgive my bad diagram, and if I've misused any words here; I'm new at this stuff!

[![enter image description here](https://i.stack.imgur.com/7X66N.png)](https://i.stack.imgur.com/7X66N.png)

Questions:

* Does this wiring make sense?
* How can I find the source of the short? I've inspected all the wires and everything appears to be sheathed correctly and not contacting any other wires or the box.
* I haven't opened the other switch which shares control over the light. Is it possible the problem lies there?
* Any other ideas, or anything else I should check?