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oh ok so basically you broke off the "nipple"...and yes your on the right track, in this case i would attempt to "notch" the remaining plastic left in the hole and use a small needle nose to try and thread out the old plastic...as far as the unions they have been sitting that way tighten for years so you will need a large channel lock to undo them (a rubber wrench may work, but the channel lock is a better option) no sealant needed when re-tightening them as they are a O-Ring seal...good luck