Rough Idle Problem- 1967 Valiant

Okeh, but why not just replace the vacuum diaphragm for a fraction of that price?
I converted the car from points, and had bought a couple used distributors which were almost the same price as this new one. For just about the same price, I figured why not just get the whole thing new so I don't need to worry about shaft wear and who knows what else. This is my daughter's car, so my main goal is reliability.