Lou,
Pop tops have not been known to be a source of leaks on the R22 unless you  
have a severe driving rain or use a pressure hose on it. Some pictures of your  
problem would be helpful BEFORE you add a rubber gasket or anything else to  
it.
Had a great day of sailing today. Winds on Hartwell were fifteen gusting to  
25. Not many other boats out though. It was nice to be able to adjust the sail 
 size for the conditions. Gotta love the winds that a hurricane brings. :)
 
Rummy