Methods and systems for improving permalloy sensitivity. The present invention also relates to olefin polymers, olefin polymer scrap andor mixtures thereof whenever recycled andor upgraded by the method defined above and articles which are composed wholly or partly of them. The external profile of a drive member which is rotatable within the drive bore engages the radially inner end of pumping plungers disposed in each of the plunger bores for a portion of each revolution to reciprocally move the plungers between radially inner and outer limit positions.