Going for it.

When the fat feeder is nearly empty and the fat is at the bottom the robins find it very difficult to reach as they cannot hang upside down like the tits.  Their technique is to fly up at the fat and stab it with their beak.  I suspect it is only moderately successful and that they probably exert more energy than they gain.  I shall therefore now go out and put some more fat in the feeder so they can eat more economically.