OK...well, for starters, those two delays are set up rather differently, with the Pitt having CV over only delay time, and the 2hp having CV over delay time, feedback depth, and wet/dry balance. Given that these aren't exactly alike, it would follow that both of these shouldn't manifest the same problem. One or the other might be malfunctioning, but both? Not likely.
So, let's look at potential user error. Put the 2hp back online and see if this is what you're doing:
1) Connect an audio source to the "IN". This MUST be a synth level audio source; if you're trying to input a LINE level, it won't work without stepping the audio UP to synth level. Line level audio is either .775Vrms (the "consumer" standard) or 1.4Vrms ("pro" standard), while synth audio in a modular typically runs between 5 - 10 Vrms depending on synth format, etc.
2) Set the "FDBK" to about 10 o'clock.
3) Set "MIX" to 12 o'clock.
4) Connect an audio destination (like a mixer input) to the "OUT"
5) Now, while listening to this, sweep the "TIME" control back and forth. If you're using a pulsed and/or rhythmic signal, you'll hear the change of echo time AND a pitch-shift as you sweep the knob. If you use a sustained sound, you might not hear the delay, but you should still hear the pitch-sweeps.