Why rebuild pop-bumpers when a quick spray of WD-40 will get things going as good as new 
Cheers
Ian
(PS, please no one take this seriously, while it is common practice, it leads to much greater trouble in the longer term. Rebuild with new sleeves as suggested 
)
Ian - Funny you should mention it - But I "drop" a tiny bit of "3 in 1" oil on the bumper spoon - especially on System 1s.
