The 501LSW or 502LSW will work very well. It will seal the existing seal’s voids. If the existing seal has pulled away from the roof and can be removed easily, remove it. If not, use the Dicor self leveling lap sealant just to fill in any surface cracks or voids. Let the self leveling properties take over and seal the existing seal. No need to coat the entire seal – just the voids.
Prior to re-sealing, wipe the area with a cloth dampened with rubbing alcohol. The rubbing alcohol will dry any moisture and clean the surface.
Hope this helps! Good luck with the re-sealing!
Safe and happy travels!
Dicor Corporation