Something is causing a lean condition if you have to restrict the carb to keep it running.
When you say the main jet is clean, is the very, very small orifice (that's vertical) clear?
Looking thru the larger hole, that passes al the way thru sounds like you cleaned that.
The small, perpendicular orifice MUST be clear (which sounds like it isn't).
If no jet tools are available, a wire brush strand, clamped in a vice grip, should push thru.
Carb cleaner should also pass thru and squirt out both sides of the jet..
.