The velocity setting usually doesn't affect the ability to cycle on a mag valve with a level 7 bolt. It also doesn't have that much affect on the reactivity of the trigger.
Check your trigger rod length. When you have the marker aired up, put the safety on and hold the trigger against it. There should be a small air gap the thickness of a credit card between the back of the trigger and the front of the trigger rod.
Usually, anything causing issues with a mag is oring related. You mentioned leaks that were fixed with a bit of oil. That means things were dried out. Orings don't last long exposed to air. Give the valve a good cleaning and check the orings. You should replace them if they look suspect or if you know they are old.
Except for the Automag in front, its usually the man behind the equipment that counts.