I don't remember who asked this a while back. About the line piling more on one side of the spool while respooling a bait caster reel. I found out that two things that cause this to happen. First you hand is too close to the reel, second it's off center to the centerline of the rod. This off center holding of the line will favor it to one side of the spool.

I just had this happen while putting new line on my new bait casting reel. Bigbill

Funny, I was going to post the same thing. I just went through it too. However, my solution was to use a heavy book as my line tensioner with the pole set up as if I were using it on the water and I made sure to crank the reel at a reasonable pace. I figured I really had no reason to rush the process. Thanks for sharing