[Mp 2.0 not ejecting brass]

I shot gun it didn't eject as well before cleaning and polish job.  My son shot today the first time the gun had not hung up with him.  He was sooo happy.  

[Mp 2.0 not ejecting brass]

Ejector was dirty cleaned and polished slide will shoot again tomorrow to see if that got it.

[Mp 2.0 not ejecting brass]

My son who is 11 shoots a 2.0 in uspsa and the gun doesn't ejection brass well.  The recoil spring has been changed to a taran tactical 13lb spring. Brass ejects about 4 in out and 6 in back.  I know some problems are my son's grip he will limp wrist pistol.  I am wondering if spring is too light?  I would like to see brass further out.  We shoot cci 115 9mm if that helps.