@staz , peter, I get the same results when I key on the service manual , either it is still in the works or there is not a service manual, there is plenty of other info./guides on the Barista, from tear downs, testing items to trouble shooting, hopefully they can help. I did try a google search also and did not find a service manual. If you have a particular problem, post your problem as a new question with all the info. and one of the ifixit volunteers may be able to help. Good luck.
Added a couple links below that may help.
I hope this helped you out, if so let me know by pressing the helpful button.
https://www.espressocare.com/products/st...
https://espressodolce.ca/parts-diagrams/...