turn lights problem

I have an 90 honda civic dx. Recently the turn lights have problem.
The front right turn light does not work; the front left one works,
but when the bulb is removed, the flashing is still normal (it should
flash faster). All the rear turn lights work fine.
When turn on the emergency, the front right flashes while the left doe
not. But after a while, the right one goes off and the left one begins
to flash. The flasher relay is fine.
When turn on the low beam, the lights are fine. The fuses are fine.

What may be the problem? Thanks.