Fx Impact POI and valve seat?

After my last post I started to think. I have shoot like 6000 pellets over my rifle. I have read a lot so I went ahead and cleaned the barrel and this is the result at 70 yards ( I clean the barrel every 500 or 600 shoots) 

70 yards 5 shoots
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I was " happy, so I continue shooting and I got this at the same distance:

3 shoots:
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and then: 6 shoots
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AFTER watching the paper I notice round holes that makes me believe that my pellets are not spiralling.

Seems all my groups are showing vertical deviation, that makes me believe that:
A) Either the regulator has a little problem
B) My valve seat it's getting broken
C) Or the o ring between the hammer and the valve it's getting broken and it's causing speed to go up and down.
Or 
D) I have seen many videos in YouTube and I'm becoming crazy in search for accuracy .... and my groups are not that bad after all....

My rifle was shooting like a charm from factory (tuned by Utah airguns) and I haven't modify anything, so I guess I will go ahead and change the valve seat ( got one from ernest) and also the o ring between the hammer and the valve seat.
What other ideas do you guys have?
 
The speed can vary a little barrel to barrel. I would think most people find a sweet spot somewhere between 830-860fps. Try shooting them quicker and see what your groups do. 
Once you find the best speed for your barrel then you can fine tune the regulator pressure so you are shooting with your hst back at 5. The regulator will give more consistency this way and you’ll get the best shot count. Harmonics are better too. The gun is happier. 
Ted and Matt both have excellent tuning videos on how to do this.