The wire quality inside the cable is junk (surprise suprise). You almost dont need wire cutters, your finger nails will do. Unless you are good with microscopic soldering I think you are SOL inside the xmitter and sensor. But you could splice just outside of each in the hopes that the issue is somewhere in the middle of the run.
As for blinking, if the senor is totally fubar'd, the xmitter wont blink. The "brains" are inside the sensor, the xmitter is pretty much just a battery, solar panel, and antenna. But really it could be anything.
It blinks at a normal rate - I'm wondering if it's the cable - it's been on the roof for a while now and some of the connections are getting a little loose - Can I just buy the cable? or is it pretty solid in sensor. It's a deal getting up on that roof - not something I LOVE doing! (steep).
My GUT feeling is that since the sensor is blinking regularly it's the other hardware.