Hi Everyone,
Thank you all for your responses. I think I have 3 options.
1. Do a little scraping and measure.
2. Find correct points and charge.
3. Send it to Jimmy.
What I'll do is wait until my mate pops over, he's a bit better than me at this kind of thing, having done some electronics work earlier in his career,
I think together we'll study the schematic and give that method a go.
I am fearful of shorting anything and/or overcharging causing a rather big bang in my little workshop.
Some of the connections seem difficult to get to without further unsealing, again something I am reluctant to do.
My universal intelligent charger with crocodile clips may be very useful but again fearful of using it as I cannot specify amperage and voltage as suggested.
I have also learned it looks like the shop did not provide a 16 amp upgraded battery as I was told and I am also pursuing the seller on this matter, as it does have a serial number and I hope I can get the original documentation.
Again, I'd like to say a big thanks to everyone and I'll let you know how I get on.