I was never a big fan of the rear P-H sight bolt that went right through BOTH backsight ears. Not a good idea as you can NEVER tighten them up because if you TRY, then it will simply close the ears together and nip the bolt-way up and therefore the bolt and it STILL won't be tight........., it's just pulling on the stand-alone ears!
Get rid of it and bolt the left side mounted sight to the left side backsight ear. Just my 2c's worth based on my limited engineering and equally limited experience as a bit-part Armourer!