In the end, it was just a dirty headphone jack. I cleaned the headphone jack with a cotton bud and some rubbing alcohol and that seemed to do the trick. Thanks to @thisdoesnotcomp on twitter for the suggestion.
Hi Joe, I just used this guide to take apart my 950 IS to swap out the screen from another one. There really isn't much different, one or two less screws to take out and the cables for the LCD look a little different but it's essentially the same process to remove it. Just be sure to keep track of which screws go where and you should be fine. I bought a broken 950 IS off ebay to use for parts so I may put that back together and create a guide for disassembling that at some point in the future. Cheers, Martin