if Trump goes into the convention with 1237 votes (and I think he probably will), his delegates are not going to vote to require more than 1237 votes for the nomination.
But what if, as we’ve heard, some delegates are being put in place to vote for Trump on the first ballot, but afterwards, they will vote for who they really want.
If so, and they’re not really for Trump, what’s to keep them from changing the rules to some other needed vote total that Trump didn’t achieve?
I don't know if those reports are true, but if so, it's a sign of Trump's political inexperience that he didn't focus on delegate selection issues until he got (legally) rolled in Louisiana.
Generally, the winner of a close contest at a convention is telegraphed by rule-change votes that take place early.
I think that such was the case with the ‘76 GOP convention, where Reagan supporters proposed rule changes, and at the ‘80 Dem convention when Ted Kennedy supporters proposed rule changes. When the rules change lost, the chance for the challenger’s nomination were lost as well.
I don’t think such rule changes have ever been successful in at least the last 50+ years.