Flathead Chirping at Temperature

[Steves46]

This is a bit odd. When I first start the motor, it runs nice and quiet however...after she gets warmed up starting at 160 degrees, this chirping noise starts to set in. My belt "appears" good and has 1/2 in. deflection. During my troubleshooting, I removed the generator/waterpump belt, fired her up and the chirp was gone. I manually moved the generator and water pump pulleys and there was no noise or looseness of the pulleys. Put the belt back on and the noise was back. I know this is ill advised but I tried some belt dressing and it really did not make any improvement. I will try to find one of those cogged generator/water pump belts and see if that makes a difference. What baffles me is that is any of the pulleys were going bad, I would think they would immediately start making the noise rather that once the engine is warmed but I could be wrong. Has anyone else ever dealt with this type of problem and what resolved it? I am hoping a new belt will do the trick. Appreciate any feedback. Steve