You know what this thread reminds me of? This!

Also this, though I'm sure you have a different problem: my first folding bike was a Strida 3.11 that I got in march 2005. It was on sale, came fully assembled, extremely cool design, and I rode it for about two years before it went into semi-retirement in May 2007 when I got my Downtube Mini. The Strida has a front freewheel system, so both crank arms look like left arms; in fact they are both left arms, but the right one is tapped for a right hand pedal. Anyway, over time the bike developed a floppy feeling that morphed into a clunk in the BB that I could not diagnose. I checked everything (I thought) but couldn't find the problem, and it still felt like the bike was falling apart. This was part of the reason I got the Downtube.

Then the left hand folding pedal on the Downtube broke a couple months later. Needing a quick replacement I thought I'd scrounge one off the Strida. Put the wrench on the left side pedal, turned it a little, and it came off in my hand... complete with a shower of aluminum filings. WTF! On closer inspection I saw the pedal was marked R. And the pedal on the right side was marked L. And the crank arm threads were totally trashed. They had put the pedals in wrong at the factory, and I had ridden the thing 2000 miles like that.