I was ready to pass your question and go to the next person because you said it was making a clicking, and I could not relate or diagnose that type of sound for that kind of pump. Thank God I decided to read to the end where you said rattling sound. that is what you should have said in the beginning.
1st, did you replace the pump cartridge or the whole pump unit? 2nd, is the pump in a different oriented position than the original pump position? The inner cartridge floats inside the pump as it rotates and if it is in an oriented position that allows it to bounce (to & frow) it will make this rattle sound; not serious but can be annoying. It is was a replacement cartridge, perhaps the new gasket and the old gasket are in place, thus allowing too much space for the cartridge and it therfore moves too much and rattles. Or, if it was replaced as a whole new unit. there is a problem with it that you should not be responsible for, except for the positioning orientation. Finally, if there is still too much air in the system, the air bubbles will jossle the cartridge untill you get rid (bleed ou ) the remaining air. Goodluck<Macgivor

I have a Grundfos pump in my home and use rain water, but it is working every 5 or six minutes just for a few seconds. i can not see why, all the tabs are shut properly and I do not know what to do. Is it something to do with the pressure regulator?
Thanks.