Note, sometimes one bulb being out will cause the blinkers not to blink, screws up the wattage match of the blinker. Either the blinker is weak or not enough current draw for the blinker to work right.
Mine is a little different (export model) but from my reading most of the front lighting grounds on the drivers side inner fender about half way (ground-G 103).
Mine has an added ground near the headlight bucket in the front, likely because of the Euro lighting.
May also be the front harness connector under the air box.
A remote chance your blinker module is weak? Universal blinkers can be iffy, they work a lot better if they are roughly matched to the wattage draw (number) of lights.
I added a ground from the battery negative to the inside of the passengers side fender like the newer models have. If the block to firewall ground gets flaky (which happens often) from corrosion (electrolysis) it may also cause issues in multiple circuits.
Check for low voltage (turn signal fuse would be a good spot to check) and ohm your grounds. A quick check is to do a voltage check from suspect grounds to battery negative any (substantial) voltage indicates excessive resistance. Ohm the wire side of a ground ring connector, the ring connector and the body section the ring connector is bolted to. Some of those ground ring connectors are crimped and corrode, some are soldered.
Check your turn signal fuse for corrosion or whatever.
Best guess would be a burnt out bulb, a ground, low voltage and/or a weak or flaky blinker.
