I bought my car back in 2010. The left turn signal *always* blinked at twice the rate of the right one. All lights operated as normal, except that the left side was twice as fast as the right.
About three years later, I learned that the left rear turn signals were no longer working. First clue was that when I unlock the car, the left rear lights didn't blink. Lights and brake lights were fine and the front left turn signals worked okay, still at double-quick.
Over the years, my local Lotus certified mechanic suggested a few fixes but none worked. I just lived with it, using hand signals. I continued to use the turn signal and only used hand signals for the folks behind me. If nobody was behind me, I was lazy and didn't use hand signals. Anybody in front of me could see the front signals.
This spring I had the car in the shop for the camshaft issue. One of the things I wanted them to do was look for a fix to this turn signal problem. In all the excitement over the cams, the signal problem never got investigated. Okay, no big deal. A few days after picking it up, I go to make a left turn. Lo and behold! The thing blinked at the same rate as the right side. When I got out of the car I could see that the left rear turn signal was magically working!
It has been working since then. Occasionally, it gets "happy" and goes double-quick again for a short time, or goes slow-fast-slow-fast for a bit. As far as I can tell, it's always working now, even when fast.
I have no idea why it decided to "fix itself" after all this time. For the six bucks, I should probably buy the above mentioned relay. But, frankly, I'm afraid to monkey with it. "If it ain't broke, don't fix it!" doesn't exactly fit here, but I'm inclined to let sleeping dogs lie.