use a good quality and sharp pointed o ring pick, stuff a rag under the piston in the base so that if a circlip goes flying it wont go down in the base, then after you insert it ensure the openings of the clips have the openings are at the 5 oclock position and at 7 o clock, i always install the base gasket after installing the rings and circlips also its alot eaiser if you install one circlip before you try and do it on the motor