[Plextalk] PTN 1

I have been given a PTN 1 to try and find a home for. Currently the machine does not have a battery. When I switch it on, it tells me there is a problem with the battery and that I should disconnect the A C adaptor. This indicates that the machine must always have a battery in it in order to work. I have telephoned Sight and Sound, and they tell me that they can no longer get the battery. I am, therefore, asking if anyone has a battery for the PTN 1 which they no longer need. If I cannot source one, then the machine will have to go in the bin, which seems a shame as it looks to be in good condition. Best wishes, Peter