Get source code
python3.6 Electrum-3.3.4/run_electrum
crashes
module not found error - 'PyQt5.QtGui'
python3.6.7-1~16.4.york from PPA
launchpad.net/~jonathonf
Anyone have any ideas?
Sounds like your problem lies with PyQT (not python).
Install it via pip3 (not pip or apt):
sudo pip3 install pyqt5
Then try again running the installer.
There is also Qt.py, QtPy and Qt5.py but i don't think you need those.
Also see if by chance, you got pyqt from system packages or that PPA, i would remove it if found (ie. sudo apt remove python-qtpy).
Best to update the OS. pyqt5 is probably compiled against the python version that came with the OS and that's why it won't work with python 3.6 that you installed from the 3rd party repo.
Be mindful that some distros are dropping 32bit support, if the target machine is say, a p4, it would be advised to plan moving to a distro that keeps 32bit support. LTS at least gives him until 2021 while non LTS with 32bit support is already dropped (ie 18.04), so be mindful before suggesting a "distro upgrade" here because it probably needs planning and backing up data for migration.
As for using older Electrum, there is little to worry. If you get the phishing message, your transaction won't commit. Just change the server and try again. The good servers show a different nag (unclickable link pointing to electrum.org) but nothing to worry about it, and the transaction does broadcast. (right click and "view on block explorer" to confirm).
btw: 16.04 provides python-qt4, I'm not sure if that's in the way, but could try sudo apt remove python-qt4 and hope no important dependencies complain.