I was recently up on the roof applying some dicor to the vents that needed some touchup. I noticed that the caulk on the front (and back) of roof where the rubber meets the front cap and rear door is cracking. I'm thinking I should remove the old caulk and reapply. How do I remove the old stuff? Just use a screwdriver? What kind of caulk should I put down to replace it? Any other special things to know? I'm not much of a handy guy, so this will be my first major caulk job.