Regarding the Satlink WS-6906 satellite meter, there is a copy of the manual on the internet at https://ftp.dipol.com.pl/TV,TV-SAT/Miernik%20WS6906/6906manual.pdf

The Satlink web site at http://www.sat-link.co.uk/store/SatLink-WS6906-DVB-S-Satellite-Finder-Meter-WS69... has an option to download (at cost) a software update.
If you want this I suggest you check first by phone or email that the new software has up to date data for Nimiq 4 and Nimiq 6

What to do:
You can try adding a new satellite yourself.  Examine the data for Nimiq 4 to get an idea of what needs to be input.

If you use the meter as a simple power meter, at maximum sensitivity, you can swing the dish sideways across the top of the orbit arc and you will see multiple tiny blips as you pass each satellite. You can peak up on any of these and repeat the sweep.

At a powerful satellite you can use your set top box or the meter to try and identify. Getting Nimiq 4 would be a good start.

Once you know what satellite you can then step along to your wanted satellite.

Satellites near your longitude and the carrier frequencies, polarisations and symbol rates are listed here: https://www.lyngsat.com/america.html