Floating timing belts

Hello.

For quite some time now, my 93 ABH has been making noises in cold condition. Let's be very clear:
In the cold start everything is as it should be. After about 20 - 40 seconds, the belt starts to flutter and strikes with its untapped side inside in the panel while running (see schematic picture in the appendix ). This circumstance occurs after about 2 - 5 minutes when the engine starts to warm up.
Had taken off the driver's belt cover once, and look, straps has play in cold condition. Not unspeakably much, but enough to attack... Warm eats tight as he should.

Have anyone ever had this phenomenon or heard of it?
Is the belt damper finished or is the belt not properly tensioned, so that the damper can not press so far?

Thank you, Micah.