Quoted from Soulrider911:I just tested a stern one i had lying around same 23-800 and it read higher, around 3.8... may try to just swap them and test it
If you swap a Stern (or Data East) coil into a Williams (Bally/Williams/Midway) make sure that you either disconnect the coil diode or that you connect the power wire to the same lug as the banded end of the coil diode.