MONTCLAIR, N.J. — John Brigandi visited the Yogi Berra Museum Dec. 3 as a guest appraiser of sports memorabilia. The event was similar to popular events organized by big auction houses at which people bring in old artifacts to see if they’re worth a “fortune.” As for autographed items, Brigandi told visitors the value of signed items is based on whether the signatures are authentic. Among the challenges authenticators face is recognizing signatures that may be faked, either honestly or dishonestly. How could a fake autograph be done honestly? Well, there was a time when clubhouse attendants would ghost sign balls for certain players. Generally, this was a time when a marketplace wasn’t so well defined and clubhouse signatures were commonplace so that all the names of players were represented. One visitor brought in a team-signed ball from the 1978 World Champion New York Yankees. It was signed by Reggie Jackson, Sparkly Lyle, Lou Piniella and, among others, Yogi Berra, then a coach. Brigandi, who has specialized in team-signed balls since the mid-1980s, said the ball could be worth more than $1,000 if all the sigs were real, but placed the price for the owner at about $400.