Hi and welcome, nice looking P38. I also came from the manta stable way back through the mists of time and owned ADZ4575 for a number of years( now owned by Simon Crook) and moving on to dare I mention a Toyota Surf and Landcruiser Colorado as well as too many Land Rovers currently filling my driveway!
Good chance the motor to change between high/low ratio will be seized through lack of use, be careful it doesn,t get stuck between the two if your trying to change between hi/lo.They are also common for door locks going faulty affecting the central locking.
Hope this helps, best wishes.
Stevie.