It has been a while, but I seem to remember there was a modification for this problem. The battery to keep the memory fails and there is a replacement battery for it, requires some adapting to fit. Take the display apart and you will see the battery pack with 2 wires to the board, cut the wires and wire in a couple of ni-cad type batteries in of the same voltage and you will be good to go. If you have a friendly dealer close they may have the bulletin to explain the update.
Steve.
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