Venezuelan stations have disappeared rather rapidly from the AM dial. They used to be heard on many frequencies some 10-15 years ago. Now many are gone, I believe mainly for economical reasons or because of censorship from the Venezuelan government which simply close downs media outlets which they dislike. A truly unfortunate situation.
Some radio stations still operate on mediumwave in Venezuela though. One of the most commonly heard Venezuelans nowadays is Radio Nueva Esparta broadcasting from Isla Margarita off the Venezuelan coast. Radio Nueva Esparta is one of the most common guests on 920 kHz. I received a short but perfectly adequate e-mail confirmation from the station some weeks ago for a reception made at Lista in March.