Someone taped the bells up to soften the ring, I freed the gongs and widened the space and let 'em RING!
If you take out the ringer by removing the two screws in the mounting wings. you should find its frequency designation on the yoke end, stamped in ink. It might be possible to see without removing it though, I can't remember. In any case, here are examples of synchromonic ringer designation on the No. 124 ringer, which is what you have.
It is probably one of 16 Hz (HB-5), 16 2/3 Hz (HA-4), 20 Hz (HC-1), or 25 Hz (HA-5) type of the size of the clapper weight. Most of these might at least ring with some intensity on a 20 Hz line. The last one (25 Hz) might be very weak. I don't think I have an HA-5 ringer to see whether it has a shortened clapper weight or not.
One of the ringers in the picture is the original ringer installed in your phone, HB-4.