Yes, adjusting the EOS switches made a huge difference to this issue.
Once I had cleaned the flipper mechs and rebuilt with new parts, the lower left, upper left and upper right were all far too powerful. The lower left flipper in particular smashed balls against the hype targets, giving uncontrollable bounces with no time to react. It also caused air balls on the right ramp. Now I have tuned it, the whole game is so much more playable as you can, with control, pick off the hype targets in order and safely shoot it up to the upper playfield too. It has given the left flipper real meaning. This lower left flipper improvement transformed the game.
You adjust the EOS so that it switches from the power coil to the holding coil earlier in the movement of the solenoid to slow the flipper down. It is crude, but effective. Marco sells a leaf spring adjustment tool that makes this really easy
I also tuned the lower right flipper too to give sensible vector scan speeds (780 is my highest now), as this shot smacks into the posts at the mouth of the ramp when you miss. Most vectors are damaged here, mine isn't yet, and I want to minimise the risks.
some fool had actually put a more powerful coil in the upper right flipper mech !!! It was stupidly powerful with the big flipper and broke a drop target and a bulb behind it too. I needed to buy a new coil and rather than buying the stock coil, I bought a slightly weaker one.
If you were to keep the original factory coil in the top right, I think that you will be ok providing you stick with the smaller flipper and adjust the eos
Having got my game so playable, I am actually considering putting the bigger flipper back in the mini playfield. It is frustrating to get the ball up there on the right ramp to then lose it down the middle ramp so quickly. I think the designers had so change of heart here. The game is designed to look right with the smaller flipper. But I think it might play better with the larger one (with weaker coil). With the small flipper the ball can often drain down the middle ramp without you being able to even reach it with the small one.
The upper playfield is very badly designed. This might sound crazy, but I am also wondering about putting a one way gate on the entrance to the mini playfield from the left ramp as it is mad that there are three ways of draining out of this tiny playfield. And it is quite difficult to get the ball up there in the first place. Just drilling two holes in the metal ramp just above the popper and making a wire gate would do the job. And to return to stock, it would just leave two small holes that no one would really notice