There are 2 flashers which are driven by 1 transistor. One switches to the positive side of the sinewave, the other to the negative side.
In the schematics these are indicated as phase C and D. (A&B are for feature lights)
There are diodes on the flashers, and a single wire to the transistor.

How many flashers do not work?
A single flasher indicates the diode, flasher or socket.
A group of 2 indicates a transistor or the wire/connector.
A group of flashers on a single phase indicates a blown fuse or daisy chained wire being loose.

What exactly is the problem on your machine?

I suggest you check all the fuses first and then start with measuring the voltages.
Note that these voltages are AC. (this is how they "made" 2 phases: the upper half and the lower half of the sinewave)