oil metering jet grommets

[steevo]

Hi,
 I\'ve just finished the rebuild on my fd,but one thing is worrying me a bit.
I noticed when i was installing the oil metering jets to the rotor housings that the second hand housing i had purchased had a tiny rubber grommet with a brass eyelet installed in the jet thread,but both of my old housings had no grommet at all.
Does anybody know if you need the grommets and did mazda change the specs on this as mines a 98 model car.
Thanks
Steve