Unfortunately those manuals are not for your model.
I am wondering if your electrical issues are all related, or maybe they are separate issues.
The tach is electrical, it’s getting its signal off the stator, which sends it to the rectifier, then to the tach. It may have an inline fuse?
The blinkers, same thing except they just get a steady stream of 12v off the rectifier, were as the tach gets pulses, so they are both connected but differently to the rectifier.
I am not sure but if you see variability in the blinkers then is it the rectifier that is doing that, or is the flasher relay sticking. I do not think it’s the relay.
Since you have more than one electrical issue it makes me think they are related, but they may not be.
It be helpful if you had a manual for your model, they share allot with the GY, however the gauges and related wiring are different.