echo base question-- developing hiss issue

[obs]

Hi guys,

I just built an echo base a month or two ago based on slacker's schematic (thanks so much by the way!).  Its been working fantastic, but I've recently noticed a rather noticeable increase in hiss and trebly noise in the delay repeats.  It's actually pretty drastically changing the sound out. 

I read that a dying pt2399 makes lots of noise, so I checked the voltages across the chip and the voltage regulator.  Both look fine, at 4.5 and 5 volts respectively, so I think the ic should be fine.

Has anyone else run into this sort of issue before, and could give me some idea of where to start searching?

thanks

tim

[anchovie]

Where did you buy the PT2399 from?

[obs]

Where did you buy the PT2399 from?

actually I think I bought it from diystompboxes