Sorry I think I may be describing the columns differently. I've counted left to right though the water is going the other way.Nope, it would fit between column 1 & 2 so it directs the flow up column 1, then would flow down column 2 & 3 and out the other valve. The fact that column 2 is the hottest, proves the baffle hasn't been fitted or has moved.
As @Gasguru mentions, you've now proven that the rad is at fault and would either need fixed, if you have/can get the baffle and fit it or replace the rad.
