I have two, four foot T12 light strips (fixtures). I've been slowly learning how to replace these. I got new ones, but can't figure out how to get the hard plastic grommet for the feed wires going into the existing strip. The thing is very ridgid. Also got a small aluminum clip or sumpthin in a small platic bag next to the ballast with the new one. No idea what that's for. Any help appreciated.