Just an update, i did lots a tests before the holidays.
Seems like the interference is mostly happening on 2 frequency, 2 and 6. I moved away from those frequency and its now not perfect, but manageable. The team is able to communicate so i have achived my goal.
We dont want to invest in state of the art equipment as we could manage to work without it, it's just more convenient to use these radios, save them some steps.
The printer don't seems to emit anything but when unplugged the signal is way better. At least now on the other channel we can communicate 200 meter. Before it was only like 30-40 meter before starting to be unusable.
Maybe someday i will bring the SDR to scan if there is something specific that could cause this but in the meantime at least it work again.
So thank you all for your inputs that were greatly appreciated to help me find a solution for my problem!
Have a good year!