BROOKFIELD, Wis. – Checking out Check 21 has apparently been on the minds of a lot of financial institution executives, judging by the attendance at a series of seminars Fiserv has been holding on the topic. More than 1,900 managers have attended the sessions so far in a nationwide series that will conclude in May, the company said. Check 21 goes into effect on Oct 28 and will require credit unions and banks to accept substitute check images, as well as train their staff in the processing and re-credit implications of the law and notify consumers of the change, said Mark Damico, president of the Fiserv Item Processing Group. Fiserv is the nation's third-largest processor of checks, with 67 centers in the United States and Canada. The final of the series of 41 seminars will be on April 7 in Richmond, Va., April 8 in Indianapolis; April 20 in Brookfield and May 12 in Minneapolis, the company said.