The Normally Closed switch is the eos for the lower flipper.

The Normally Open switch provides the power to your upper flipper, but not until the lower flipper is at the end of its stroke.

It is set up to provide maximum power to each flipper sequentially instead of both at the same time which would make them both a bit weaker.

Did you reconnect zactly as it was before?

If it works when you manually close the normally open switch then it’s probably hooked up ok.

Move the flipper manually (not just closing the switch)

The normally closed should open completely (so all power goes to upper flipper) and the normally open should close completely (so there’s no resistance to decrease power to upper flipper)

You may just need to adjust them (bend slightly) to get that to happen. In the stack there are usually harder metal pieces that are already bent for each switch. You adjust the amount of bend to control the gap width and ensure full opening and closing of the switches. Maybe not on Bally’s so you may need to bend the lead switches themselves a bit... I’d need to check mine to see if they have them.

Also assuming you didn’t change the eos switch on the upper flipper too? If you did then it may also be the problem and need to be adjusted.

It’s all about the gaps!

From picture it doesn’t look like you have the extra metal bar to adjust the switch in your stack.

Slightly bend the left most piece inwards to make the gap on the normally open a bit smaller... but not so much that it is closed before the other switch is fully open.

Also check with you press the button that there is no electrical arcing on either switch when engaged (ie closed is fully closed with no arcing, and open is fully open with no arcing.