I tried putting my pushrod in with the retaining rubber on it, and it just slides in and out. Without that machined groove in it, there is nothing to catch the retainer, so I don't know how he expects this to work without it??? If you re-read his ad, it's says that this are machined for the retainer, so if you have one like mine without it, than that is a problem that he needs to correct. I haven't gotten an email back yet, but I'll post what his reply is.