[dagskarlsen]

]It is a little bit more struggle to take it down to the basic way of testing, but its hard to fail. The clue is to have some 9V batteries of the pictured size. (Reason: high internal resistance compared to most other power sources)
1 battery between Red and whit, and the phone should work in hence of going off hook and hear yourselves. If you take 3 batteries in series as pictured, the 27V should be enough to move the clapper fort or back depending on polarity.

2 wires from terminals for ringer-motor Ø4 and Ø16 that are touching the batteries + and then changed forth and back should make the clapper move. If it moves, but not hitting the gongs, the gongs should be turned to the clapper hit it, but not are resting in touch with it.