Provost however was not interested in remaining with the show , and did not renew his contract .
As the eleventh season of Lassie approached in 1964 , series star Jon Provost was a fourteen - year - old with his contract up for a three - year renewal .
Provost was not interested in remaining with the show , and did not renew his contract .
As the eleventh season of Lassie approached in 1964 , series star Jon Provost was a fourteen - year - old with his contract up for a three - year renewal .