Without pics or video it's hard to say for sure (and I hope you're still around to see this!), but here are the areas that seem to be most likely to cause problems in an FCG-type mechanism like this:
1) You said you hadn't installed the puppet yet - did you put any kind of weight on the line? Without a weight, the lines have no reason to pull back up away from the motor hub, and are liable to get caught up in the arm.
2) Can the lines move freely in their tracks, or do they seem to snag anywhere?
3) Can the washer rotate freely, even under pressure? If it's getting snagged, the lines will tangle.
4) In most of the puppet master designs this wouldn't be a problem, but just to make sure - are the eye hooks located well above the level of the motor arm? If they're too close, the arm can catch the lines as it swings and wrap them around the hub.