Hello and welcome from NW Wisconsin! To help people volunteer effectively:
1) asking for a volunteer to speak up from a large group is rarely successful -- do the ask one-on-one and promise to provide support.
2) when a volunteer or a small committee has accepted a task, don't let others second guess them and try to override their decisions -- this is very disheartening.
3) look hard at the list of officers/positions -- are all of them really needed? -- have times changed so that the positions should change?
4) be sure to say thank you for a job well done, both publicly and privately.
5) be sure to involve new members right away -- not by asking them to take on large tasks, but by hooking them up with other members who are working on a project -- start to give the impression that some extra involvement is expected of everyone -- if you say it often enough, people will come to believe it!