These youtube videos are for a Boler, but it is identical to the procedure for installing new window gaskets and lockstrip for the Scamp. This is not a job for the faint of heart.
Glass shops will still install new lockstrip for you and can even cut new plexi or lexan windows. May have to call a few to find one that will do it.
Scamp Trailer parts department can send you the lockstrip and gasket for the windows as well as new windows if you need to replace those.