As promised I did some experimenting with the cheap pair i bought (For just $40!!).
One side works flawlessly while the other had 6 out on the indicator and 3 out on the brake, here are the pics:
From looking at all of the other reports it would seem these particular sets are pretty much the exact sets that go wrong for people.
So what I did next was take a dremel and make some peek holes, note that the space in between the back plastic and the PCB cannot be accessed by splitting the light as other posters have found, so this is the only way to get clear access the PCBs.
The big hole on the back gives you access to both the first banks of LEDs and the main cable connections, i re-soldered all my wires to be sure while it was opened up.
I would advise once you have re-soldered the LEDs that you patch these with electrical tape, or as im currently doing, 3d printed patches to glue over the holes.
Now this is the real reason these units are having problems, dry solder joints, they will likely work from factory then randomly fail, or fail but work intermittently as they get knocked about by day to day use on the car.
I worked my way along the clusters through the peek holes, resoldering both positive and negative pins on the LEDs each hole gives access to.
Result:
Fully working set of Valenti tail lights for $40, score!
Note: It has been mentioned in previous posts that you should pull out the cables a bit from the hole to stop this issue from happening, I can tell you now, with complete certainty that this is
NOT the issue, the issue is dry solder joints, hopefully someone from Valenti can be shown these pictures so that in future people with this issue within warranty can get them exchanged.
Since i bought this used for cheap I had no warranty and thus nothing to really lose, Don't attempt this if you're within warranty, just get them replaced!
Patching the holes:
Not super slick but it does the job.
Anyway, to make this super clear.
1) The LEDS are not blowing
2) Moving the wires on a working set will not prevent them from failing if they were going to fail to begin with
3) The fault is 100% down to dry solder joints failing
4) Warranty replacement is your best bet, or do what I did if your warranty is expired