Originally Posted by pablo040

It's not as much a "problem" as it is an issue being experienced by newbies (first time kit builders). Thus it can come from anything as simple as using Allen wrenches instead of hex drivers, not having the proper sized hex driver (standard instead of metric), not taking the time to pre-thread thread most fittings to ease assembly, to not being patient and trying to rush assembly.
Experienced builders aren't really having any problems.

Otherwise, read the last few most recent pages as most thongs have been covered at least twice already. Have fun!