In speaking to a parts vendor a few years ago, about buying parts to repair a gas shut off valve, he said he had many used gas shut off valves that he had collected over many years.
In trying to repair all of them, he made fittings to test same with air pressures under water, made devices for lapping the existing parts etc., & carefully tried to repair them.
I think he said out of about (30) he tried to repair, about (2) did not leak, & about (28) leaked, so he recommended buying a new one.
Few are repairable, but in my humble opinion, its like playing Bingo, all one hears about are the very few wins -- & its also almost like playing Bingo to try to win a Wal-Mart fire extinguisher -- the money one spends playing Bingo, & the time wasted playing Bingo, one could have just bought the same fire extinguisher at Wal-Mart.
Just think!
For under $40.00, your wife's hand will not smell gasoline, your's & her investment will be protected, & she will greatly appreciate this new gift -- after all, what lady friend wants used, repaired items like old used, repaired worn out shoes as a gift.
Just a sincere humble opinion, plus you'll have the happiest wife in town.