Gödel's Loophole

We don't know the loophole. We can only guess.

If we alter the Constitution to make it easier to alter the Constitution then it could become a runaway problem, leading to dictatorship.

But something obvious the senate can block is not it. An amendment that gives the presidemt power to suspend congress during a national crisis or for national securitu will do the trick too, it is a bit obvious but people might be ok with it if a crisis or war is big enough. The only thing preventing a dictatorship is the senate who serve longer terms than the president. Being able to suspend the senate (the VP had a role!?) without an amendment is even more powerful if the majority party is for the dictatorship. General elections can be delayed indefinetly.