In article ,
John wrote:
I took off the radiator and the holes that the brackets are plugged to
are enormous (and of dubious geometry). I cannot put the brackets in a
different location due to the lugs on the back of the radiators.

If it's a solid wall, the quickest - although perhaps not cheapest - way
might be to enlarge the holes further to take expanding bolts - you'll get
them in the sheds. They're just about the right size to fit between two
brick courses if this is why the originals have pulled out, and they
certainly won't. ;-)

--
*Why is the man who invests all your money called a broker? *

Dave Plowman London SW 12
RIP Acorn