@@k-tk こちらこそ御免なさい。日本語が初心者だから上手じゃないです。For more complex sentences and questions I want to ask, I use a translator (which isn't correct/accurate). What I meant to ask: Is it recommended to remove old needles every year? Or, is it only done every other year? Or, is it only done every 2 or 3 years?