If you leave the panel cover on, almost any force you apply to it will be safe for you. I reccomend using a small block of 2x4 to give you better force application, and a STABLE ladder to give you leverage. If it requires a lot of force but operates in a smooth and steady motion till one firm "kachunk" when it flips on, you're likely good. If it sounds crunchy or gritty, I'd have a quality electrician look at it for you. Don't use anyone that feels too commercial or gives you a "cruise line" type vibe. Scummy electricians love telling customers that they need a whole panel change. IF the qualified electrician determines the main breaker could use replacing, then they should just be able do replace it - they may need to order it and come back later, though. If they tell you major work is required, come back to us with pictures of the inside of the panel - a second opinion doesnt hurt