Both Flipperfinger are weak; what could be the cause?

Does a chime with 3 sounds by Williams also work in a pinball machine by Bally,for example inside "Old Chicago"?

Then it´s possible, that also works with a Williams chime box; but I think Williams is for 24V and it could be a problem with the solenoids....

What can I do to make the chime box in my Bally Old Chicago quieter;
the chime box is not an original Bally but by Williams; the 3 Solenoids which are working are originally from Bally "Zip A Doo" and should work with the proper voltage (50V)

The solenoids which I had built in the chime box have the number: two with A-25-1000 and one with A-25-1050;I know they are not the originally for the chime;
the originally Solenoids are CC-31-2000,but I don´t have this one; I had given new pads.

I measured the coils;two have 7,5 ohms and one 11 ohms
What does "2000" on the coil mean? does it stand for the winding number?

Could I install a resistor in front of the coils?
The Coils designated "CC-31-2000" are read from the part list of Old Chicago for chime