It sounds like you've done it perfectly. I'd suggest trying a different heatblock, but I doubt that would make a difference. Make sure they are all aligned in your extruder with no obstruction when you look through end to end.
I've had to do some heating and cleaning of my heatblock and heatbreak when replacing parts to remove bits of plastic. (Gentle wire brush and a burner lighter).
The only other thing that comes to mind is your thermistor or heatblock cartridge being damaged and reporting the wrong temperature. Temps too high or too low can lead to clogging.
If I were you and I had tried all these things, I would get a new extruder and see if that fixes the issue.
I have the S1 plus. I've upgraded everything from the bed to the extruder.
The biggest benefit I've seen is from removing the stock software and using klipper. It's a lot to setup and calibrate, but it works well.