Gen9 trigger jamming

Any fix to the gen 9 m4 trigger jamming on semi auto? Its not slipping off the trolley it seems to jam but only in semi mode

I recently brought a JM Gen 9 M4A1 and also noticed my trigger would partially bind up half way through the trigger pull. I took the lower apart down to the gear box to see what was causing the problem, i figured it was inside the trigger mechanism but later when i reassembled and test fired it the trigger didn’t bind up anymore.

All i would recommend is a quick tear down of the lower and see if there is any loose parts or bits of plastic around the selector transfer bar and the trigger.

I have also heard replacing the trigger with a metal after market one will get rid of the issue. (Though i have yet to test this.)