Regulating is too touchy

[BobG]

I’m fairly new to this and have worked on maybe 30 or so vintage and new movements. I recently went through a NH35 movement that I picked up with low amplitude. 140-150 degrees and impossible to regulate. I did find that the train bridge was not flat and when the screw nearest the barrel was tightened the wheels no longer spun freely so I replaced that with a spare and all good. 
I cleaned it and lubricated it, including the balance cap jewels and it came right up at 220. I could get the beat error down below 0.5 but I’m chasing the rate all over. It will be down -15 and I’ll just touch the regulator arm and it will be up +15. This is a practice movement for me as I want to learn and improve making positional error corrections on the Etachron system. 
The amplitude has fallen off a bit as well, 200. I’ll let it run overnight but is there anything I’m missing that can cause the rate to change so significantly with a very very small movement of the regulator? Could the hairspring be damaged and very particular to both the  regulator and stud position? 
Could the regulator pin positions off? Either too open or closed?  

[HectorLooi]

The terminal curve of your hairspring might be distorted. If the curve is perfect, the hairspring should remain in the centre if the gap of the regulator pins when the regulator arm is moved along the entire curve. And adjusting the rate should not affect the beat error.

However, reshaping the terminal curve is not easy stuff. Maybe at this beginner's level, getting the watch running is already a commendable achievement. 

[Nucejoe]

5 hours ago, BobG said:

It will be down -15 and I’ll just touch the regulator arm and it will be up +15. 

Concur with hector,

 A kink or twist  in hairspring, exactly at regulator gap  can cause this, so move the regulator arm to exposed hairspring ( H/S ) there and check with high maginfication. 

Regulator slot not wide enough or nearly/ fully  closed, the gap just limits breathing of H/S.

Damaged regulator gap,  a close up high maginfication of the gap helps. 

Is regulator arm fitted fully in the setting groove?  

Good luck.