I am VERY happy to report that the circuit is working now! After double-checking the resistor and cap values around the PT2399, I also noticed some shoddy soldering around the socket, where the pads were not completely covered. I re-soldered those spots, and miraculously the effect worked. Funny, whatever I fixed also reversed the feedback knob's connections, so I had to switch those around, which means I had them backwards. After that, everything appears to be working fine. Although I do hear some faint ticking, no matter where the speed and mod knobs were set. It only goes way with guitar volume pot at 0. I will check out other folks' solution to this shortly.
Thank you Ian for the great support. IMO, this effect approaches the sound of my Space Echo, and is the better alternative for live shows.