AnthonyL wrote:
He can't find the instructions though it doesn't seem that hard to
operate, but there is a low battery warning. I guess this is
understandable anyway after 10yrs but I can't find any instructions as
to how to replace them, or what regular maintenance is needed eg
lubrication.

Not sure if this is the right manufacturer, but it looks like a standard
'UPS' style lead acid battery:
https://www.amazon.com/AmeriGlide-Pl.../dp/B087D6P58C

which are available in the UK for roughly the same price. This supplier has
been recommended on another newsgroup for UPS and their batteries:
https://www.ebay.co.uk/itm/184853002168

Theo