First the dial at the bottom on the right - I think that's a room thermostat, so where you set that should affect how the heater performs and needs to be used alongside the input/output controls.
The difference in heat between top and bottom - sounds as though the hot bricks are on their way out.
Unfortunately the Berry Magicoals are no longer made; they seem to have gone out of production 20-odd years ago. You can still get some spares for them, but if your heaters are that old they're likely past their best anyway.
Peter S
October 2008
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