I couldn't resist, I took the first coupler issue, and I see what's happening. The knuckle is too wide at the rivet attachment, and it crushed the spring when it was installed. Of course, that made the coupler stick, and it was prone to release. The couplers being too tight is the thick black paint on them, it would be better if they used the knuckles with the anodized black finish on them, they would be thinner and probably allow sufficient clearance.
I removed the knuckle, filed down the hub width, put a new spring and rivet in it, and it's running around behind me on an O36 figure 8 torture test loop to see if the car will decouple. So far, so good...
