Helm Inc. is the source for the official service manual here in the USA. I don't know if they also provide for other countries. There are many other sources that have pirated photo copies for much less cash. Officially a forum moderator or administrator (and perhaps even any of the membership... technically) cannot recommend non-official copies of anything for legal reasons. I'm just saying they are out there.
This link is to the SM for both Standard and Deluxe models in the USA.