Scott Swartz's PT 80 Echo...thumping, need help

[Skidood]

Hey Group
Newbie here.
I've built this effect using the PCB and info from GGG.com
I am 100% certain I havent done anything wrong, yet the effect sounds like it is thumping or stuck in a loud, low frequency oscillation, the op- amps are working, as it passes the raw signal thru OK,...replaced the compander chip once, no change....Has anyone tried building this effect, and what were your results?
Thx a bunch
Drew

[Skidood]

Just to update..looks like the compander chip was faulty...now she sounds amazing..