The 5030 didn't have a dedicated service manual. The info for that model is found in the large OEM service manual set entitled 10 and 30 series service manual. The electrical schematics will be found in the appropriate electrical section except for late production tractors (with electric fuel shutoff instead of manual cable shutoff) The final volume of the set has a supplement that covers these late wiring changes. Follow the link for an online search (keyword 30 series). At the bottom of the page is an email link and 800 number to call. You may be able to buy the relevant volumes of the set rather than the whole.
I know of no other source for what you are looking for.