Anyone have a favourite RJ12 cable tester? Ideally that gives a clear audio warning after you've told it what kind of cable you're expecting (in my case 4 wires, maybe that's RJ11). And that indicates which wires are concerned in the issue, to aid figuring out which crimp needs redoing.
They tend to look pretty similar with LEDs at each end that flash in sequence. Problem I just had with mine (a cheapo) is that somehow I missed a crossed-wire scenario, which resulted in several blown buck converters on my boards (I thought it was a snubber issue) and a lot of wasted time.