Sometimes these wiring problems have to investigated in baby steps. These bulb holders are well known for a variety of problems.
First thing: Red wire is for the side lamps (called marker, running, parking, etc). The left side flasher wire should be green with a red stripe.
The right side (we call it the passenger side) is green with white stripe. This according to the original BE wiring diagram. Don't understand how it could be green, as that is 12v. power all the time through the second fuse (first fuse is for the horn).
Get yourself a 12V. test lamp, or use a volt meter (if you know how to use it). Disconnect all three wires from each of the flasher/side lamp sockets in the front. Don't let them touch each other or anything else. Connect your test light between the red wire and the black wire. Your test light should light when the lighting switch (at the ignition key) is turned to the first and second position. Record the results. Now disconnect your test light and connect it between the green wire and the black wire. The test light should flash on the right side when the flasher switch is pushed to the right, and on the left side when it is pushed to the left. Record the results. Let us know the results and we can provide additional help.
Also, are you sure this is factory wiring, or has someone made their own harness?
Cheers,
Scott in CA