Hi Pat,
Good suggestion below, but before forking out for a plumber, try this.
The leaking radiator could have allowed some air into the water cycle, so as long as the leaking one is now shut off and no longer leaking, try bleeding the other radiators, starting from the lowest and working up to the highest radiator.
Hopefully you wil get a hiss from some of them letting some air out???
Good luck....
Lest, October 2008