Historical clue formulations

• Machine waiting to enter the middle of this grid, as suggested by the answers to the starred clues — 2024-12-01
• It resurfaces after 20 minutes — 2022-11-12
• Between-periods equipment — 2015-10-21
• It's driven over the ice between periods — 2010-09-14
• Machine on a skating rink — 2008-02-20
• Ice machine — 2004-06-20