A clicking relay doesn't necessarily work if the solder joints have cracked on some pins but not the coil pins. I had it fail on me recently, and it started intermittently at first too.

Here's what I found on mine, cracked solder joints:


A simple resoldering of all joints would resurrect this relay for the next 25 years or so. Simple and cheap thing to do before condemning a much more expensive part (esp. if you go for a Bosch pump).