It can take some time as the paint stripper needs to be absorbed by the remaining gasket material so it can reach, and soften, the bond at the surface. Repeated applications may be necessary to “help in removing gasket material “. It’s not very effective in dissolving carbon. Depending on the material & the location, it may not work 100%, but my experience is it’s been worth the effort. Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.