Hi consumer - sorry for the late answer!
pictures of the connections don't really work, because there are so many (you would end up in one of those riddles for kids, where you have to find the correct path for the mouse to get the cheese

)
Besides the power connection, all wires from the Extra9 PCB go down to the NAVA PCB - most to the bottom side, just the 3 on the far left, to the top side of NAVA PCB (to Attack pot).
For for making the connections you just have to match the numbers of the connectors with the solder point on the NAVA PCB according to the manual. You can ignore the additional labels in the manual.
The connectors on the Extra9 PCB are numbered from left to right( on top side - pin 1 is a rectangular solder plate). In the manual there is a picture of the NAVA silkscreen of that section - bottom side. An arrow plus the corresponding number points you to the connection of each wire.
Again:
- red boxes indicate parts that have to be removed before making the connections
- purple boxes indicate parts that may not be removed for connections
- blue boxes indicate parts that don't get a connection at all but have to be replaced by a different value
I know it might get a bit confusing in the beginning - but it's really just following the numbering.
For power connection I really rcommend to connect it directly to the connector on the NAVA IO board in parallel with the wires coming from the NAVA Main board. Use the connectors included with the Extra9 Kit - 2 options: crimping or MTA-156.
Optional CVYes Cutoff CV - mounting the input and attenuator may be a hassle because there is only little space left. I would try to go at back plate, on top of the Instrument outs...
Voltage TestingI'm not 100% sure about your question - are you reffering to the supply voltage testing of +15V/-15V/GND/+5V or the scope points on the PCB (ENVs, etc)?
- as for the supply voltages, these are not changed! but no, there are no testing points indicated on the PCB.
- concerning the scope points.. that is a difficult but good question
! Generally I would say, that you can keep going using the testing points on the NAVA baord since most modifications wont change the overall oparation but make a decay-time or a tuning etc. variable - but I'll go thru it and may make a detailed list
In general I would recommend assambling the NAVA first and bring it to life befor beginning with the Extra9... it may be much easier for troubleshooting. Just keep in mind that some of the parts have to be replaced later. Just dont attache those parts fully to the board and use just a little solder - make it easy to remove the parts later!