Clanking noise from back wheel while pedaling

[Paradooks]

I have a problem with my Radcity 4 and Radcity step-thru 3. There is an on/off clanking noise coming from the backwheel while pedaling (assist mode) with weight on it. I have gone through a series of trouble shooting with rad support and had people adjusting the spokes. I also tried to use the tool and make them tight myself. However, it does not go away completely and I still have the issue. Am I missing something? I purchased a tension meter and tried to adjust them correctly and it didn't work. Asked a bike mechanic to adjust it for me and it did not work. I keep getting it doing the hills. Any suggestions would be appreciated.