IP pump makes a loud click after I took it off...

I took my IP off to replace the nut on the driver side bottom that has the rev limiter (i think) and too put a new seal on the oil neck. I cleaned it up and i turned the gear a few times and it didnt click and now (a day later) it clicks loud. what is it that clicks? BTW, the pump looks brand new even after 260K. i guess the oil and grime on it kept it like new! /ubbthreads/images/graemlins/wink.gif .................Gibson