Strand Dead

UPDATE: My Mom sent me the following.  Any tried one before?

Ah, it's that time of year... men cursing to themselves, fighting with globs of xmas lights, and nearly falling off ladders. Today I spent nearly 4 hours going through every bulb on a pre-lit Christmas tree trying to find why one section wasn't lit. I pulled out every bulb and swap it with a good bulb, and worked my way down the tree. My fingers are sore. I have blisters. And I still never found the problem. The solution? I drove over to Big Lots, bought 2 new strands, and ran them in the bare spots.

The question is, how do you diagnose a problem like this? I'm sure I made it worse by removing each bulb and putting it back in. What's the chances only 1 bulb was the culprit by the time I got done? There's got to be a better way? Thoughts?  I set my non-pre-lit tree up in less than an hour.  I'm thinking having the lights separate is a good thing.  Kinda like buying one of those TVs with the DVD player built in.  You're just asking for trouble.