Brand new belt is squeeling

[RMcG]

About 10 days ago, I noticed that the serpentine belt was screeching for about 2 seconds sometimes when I first started the car. So I followed the advice I got on this forum on thread 59231, see
http://www.yarisworld.com/forums/showthread.php?t=59231

I ordered a new belt from Rock Auto. I installed a new belt about 5 days ago and everything went well. I followed the instructions in the videos at the links posted by 06YarisRS, see

https://www.youtube.com/watch?v=B8EzgkgE25M

https://www.youtube.com/watch?v=84xtpk8xCi4

I slid a pipe over the handle of my ratchet wrench handle to get extra leverage when loosening the bolt the alternator pivots on. This was recommended in one of the videos (they used a "shotgun barrel" rather than a pipe). I used a magic marker pen to mark the metal slot that the top alternator bolt slides in. I used a pry bar (as suggested in the videos) to tighten the new belt by returning the top alternator bolt to the place marked on the slot.

THERE IS ONE REMAINING PROBLEM, HOWEVER. I notice now that the belt is still screeching for about 2 seconds sometimes when I first start the car.

In addition, the squeeling seems to follow the pattern noted on this youtube video ( https://www.youtube.com/watch?v=HRrVMtyIqIY )which I discovered through this forum, of the squeeling occurring when the ignition key is turned quickly, but not when the key is turned slowly. The video theorizes this is due to the onboard computer not having the time to tell the alternator to decrease its loading. I'm not sure about this theory though.

I just checked and the bolt on the alternator is still in the position marked by the marker pen. And the belt seems appropriately tight and in position.

QUESTIONS: Does anybody have any suggestions? What should I do about this screeching? Should I try tightening the belt even further?

Thanks,

R.