Hi all
Just a short note to say :
Firstly, thanks for your input I sorted other things as it was pointed to me while investigating this fault.
Secondly, the knocking noise is gone the rubber that was on the spring shaft was not aqueduct enough to act as a pump stop I made one from some old bushes and fitted inside the spring. I am pleased to say it worked well and going over the potholes there was no knock was good proof!
lastly you can fit the below as a substitute:
https://www.google.co.uk/search?espv...oVChMI7-zjrcvx xwIVyGrbCh2MPQRf