The easy way to tell if the CPS is giving a clean signal is to listen for the fuel pump prime, if there is no clean signal this will not initiate priming.
They do break down and operate sometimes intermittantly, but have more trouble formthe connector than the sensor itself, as the pins inside the male/female housing get old and lose thier grip.
New housings are available form POLEVOLT.CO.UK, if this is the problem.
On the phase sensor the top wire(RED) must be on the terminal nearest to it.
So long as the alloy pully has metal in the ends(lugs) it will work fine.
tabetha