What happened to the molecular stabilizer?
In “Let’s Hit The Road” Parvo stole an experimental gene splicing device called the molecular stabilizer. It was his hope that it would make the affects of cano-mutation last so he could take over the world. Fortunately, he never got a chance to use it. The Rovers managed to take it from him, it was last seen in the hands of Shag. Though, I have no proof, my guess is that it was returned to its rightful owner. After all, the Master has mastered (no pun intended) the mutation process so it was little use to him. And the Rovers are the goodies of the show so they would never keep something that did not belonged to them.