I have a friend with a Zefal Plus(?) floor pump. It's one of those double- barelled jobs that pumps on both the up and the down stroke (blue delrin or polycarbonate pump body.)
Problem is, it will now pump only on the up stroke (kills the back!). There is almost no resistance felt on the down stroke, nor is any air pushed out the hose.
We've tried pulling it open and putting grease on the plungers, but this hasn't solved anything.
