One of the most valuable parts of the service manual is the voltage reference calibration. Without it, your EBL 99 may overcharge batteries (shortening their life) or undercharge them (causing system fails).

Abstracted steps from the manual:

A multi-step process requiring a digital multimeter, variable load bank, and an oscilloscope.

Websites like badcaps.net, eevblog.com/forum, or repair.wiki sometimes have user-uploaded service manuals. Search for "EBL 99 schematic" or "EBL 99 repair thread."

Exploded diagrams with part numbers for:

Here is a simplified procedure derived from typical EBL service guides:

Problem: Unit powers on, but USB ports do not work.

All of this is impossible without the reference designators from the manual.