There certainly does seem to be something keeping electors faithful...
Is there perhaps some sort of impeachment or recall process that voters can resort to if faithlessness of electors is in danger of turning an election?
Well, to avoid the problem entirely, just choose electors who are really committed and are dying to cast their vote for the candidate they’re pledged to. Plenty of true-believing party loyalists would be willing.
That’s what usually happens, anyway. Which, again, is why I’m not worried. If faithless electors ever became an actual practical concern, the parties can just make sure it doesn’t happen by choosing the right people. People who are certain to vote the way they’re supposed to.