Cave Dweller 1 echo madness

[Kartoffelkopf]

I assembled my home etched board for the original Cave Dweller (2012), and was had it on the test rig today. Time and Dwell pots are working as advertised, however the there's something not right with the Echo control.  It's fine until close to 9 o'clock, after that it becomes a mess.  Infinite repeats, oscillation... much like the dwell control after 12, but cleaner (at the start, anyways. After a few seconds it begins to distort the output).  From what I gather, I should be able to turn the Echo right up.  I checked for solder bridges but can't see any.  I'll have to nab a better magnifier from work to check for sure.  Any other ideas that could help point me in the right direction?

[matmosphere]

The echo and the dwell controls are pretty interactive. If you turn the dwell down does it still act the same way?

Have you tried different pt2399 chips?

[Kartoffelkopf]

Yes, it behaves the same when the dwell control is at 0.  I only have the one PT2399 on hand, unfortunately (it is socketed, of course).

[Kartoffelkopf]

I reseated the chip and still had the same result.  I ended up taking the echo pot out, adding a 10k resistor between lugs 1 and 2, and rewired it.  That seemed to tame it.  Did the same with the dwell pot, just to coax a bit more space out of the first half of the taper. Boxed it up this afternoon, been playing with it for the past 3 hours.  It's a very cool delay, one that's right up my alley.

Edit: I wrote 20K, meant 10K.