Try to avoid focusing on age. Instead, you should try to meet this person face to face and say, "I understand the previous person didn't work out. I want you to know how interested I am and what a perfect fit I'd be...here's why..." You can say you recognize how difficult it is to hire the wrong candidate -- and that you know they don't want to make that mistake, but that for all of these reasons you know you'd be the right match. You can also say that at this stage of your life, you have the wisdom and experience to recognize where you'd be a good fit and where to flee...and that you might not fit the profile of the typical applicant but that you're sure they won't be disappointed with you. Let me know how it goes -- you can do it!