I ordered a QFR with reds from Amazon Warehouse Deals and it had a non-working left alt. Instead of RMAing it, I decided to open it up and tackle the problem, for the sake of science! Just as some people have guessed, it was caused by a bad solder joint.I'm sure a lot of bad boards have already been returned to Cooler Master and newer batches have had this issue resolved by now. But I decided to take some pictures and make a post anyways in case people run into an intermittent alt key in the future outside of warranty, or live overseas where RMA shipping would be ridiculous.Here's a look at the PCB underneath the left alt.A closeup of the bad joint. You can see the line from the bottom left breaks before it reaches the joint.I first tried to add a little bit of solder to see if i could close the gap, but it came clean off.I scratched off the green coating to expose the tips for resoldering.The gap was too big, so I had to use a bit of copper wire to bridge the pins.Soldered and fixed.