Pretty sure I used a narrow thin-bladed screwdriver to prise out the clip, then could get circlip pliers in.
A cautionary tale - I bought a rebuild kit from eBay. No reason why it shouldn't have been fine for the job, good seller
feedback etc., only when I came to fit it I found the Check Valve was larger across the corners than the bore diameter.
Seller claimed his kits were all the same and nobody had ever reported a problem before, but back it went as it was no use.
Ended up using one of the aftermarket kits from DS which worked a treat.
