https://www.rotax-owner.com/en/videos-topmenu/elearning-videos/231-914press136 shows a nice video walking through the process of how to adjust the fuel pressure regulator.
However, it kind of cheats when it actually shows adjusting the regulator, when it switches to some kind of unencumbered and easily attainable view:
The reality is that the upper side is easily visible, but the regulator adjustment is on the lower side:
So getting at it looks more like this: