I learned that when setting an EOS gap on a flipper, you should ALWAYS double check the gap via and actual button press.
What I mean it that manually moving the flipper bat to full extension is often further than the actual flipper button press. This distance in travel seems to be larger on Sterns than on WMS and Bally and I assume it due to the tolerances in flipper linkage.
In short, ALWAYS check gap with real life button press the actuate the flipper. DONT trust manual movement of bat to set a gap.
Also, be sure to have plenty of TIP, Mosfet, Drivers, of different/ typical number on hand.