Most likely the original sealant is/was butyl tape. Depending on the age of your RV the entire length may require re-sealing. When you pull the end loose, the seal may be compromised for several inches further back from your working area. Butyl tape has been used successfully for many years in the RV industry. If you choose not to replace the entire sealant length, using Dicor sealant above the drip rail should be considered.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"