The American Legion post in Vermont’s capital has a simple method to help attract new members: a sign in its Main Street doorway says ‘‘members wanted.’’ Like many legions, Montpelier Post 3 has a bar, a pool table, and televisions where members are bound together by military service, an experience few who haven’t participated in it can understand. But post leaders say being in the American Legion is much more than a veterans club. They still get new members, sometimes veterans of Iraq and Afghanistan, but few of them are young; most are in their 40s or even older. Post Commander Dick Harlow said young veterans have so much going on that few have time for outside clubs. The Montpelier post is healthier than most, but they are still looking for members.