Something called E6000 is the best of the clear silicones that I have tried. Behaves much the same as the old Shoo-Goo, Goop, etc. and is stronger, though that's likely not a high priority for you in this application. Comes in a gray (2 oz.- have seen larger) tube with prominent "E6000" legend. At hardware stores, big-boxes, possibly large grocery super-marts. [I have also seen a more finger-sized tube labeled something like 'E6000 Industrial-strength', but the original product seems plenty stout, has been around for decades.] Allows for re-positioning but, as with any sticky-goo, you don't want to get the stuff where it doesn't belong. Over-generous application results in PITA squeeze-out; suggest a fairly sparing application, spread into place. Skins over fairly soon and tends to cure in the tube over long-term storage, once opened.