Line 6 DL4 craziness

[el Reclusa]

Hullo, all!  First post here.  While I'd've preferred this first one to be about making something new, right now my mind is elsewhere...namely on this janky DL4 of mine.

Here's the scoop: purchased used from a fella who said it had the ever-present problem of the echoes being quieter than the direct signal, and that it was beat, and had a mod that had been performed some time ago, but was removed with no harm to the pedal's functionality...

When I got it, it was definitely worse than I expected.  The echoes on some presets were almost inaudible, but fine on others (including the looper, which was the main reason I wanted one of these).  Anyway, after having read a story somewhere on the web about someone having one of these that wasn't functioning properly giving it a good cleaning that made it magically come to life, thought I'd give that a try...

Miraculously, it worked (well, mostly).  For a few weeks, the pedal worked A-OK with no issues at all.  Having disassembled it and given it a very thourough cleaning, I figured it, being older, was just dirty. The de-installation of the mod in fact seems clean and well done. Fast-forward three weeks or so, and now it's acting up again.  Sometimes it's fine.  Sometimes the loops are almost inaudible, but the regualr delays sound fine.  SOmetimes it all works fine for a while, then seems to just sort of stop echoing.  Sometimes resetting it to factory settings makes it work right, though usually only for a short while...

Any advice?  I don't think the pedal's totally toast, a lot of the time it works just fine.  I like it, so I don't want to give up on it, but it's a little over my head as to how to proceed without help.  Thus far, I'd say I'm one or two notches above absolute beginner with this kind of stuff- I've been able to repair a couple of friends' analog pedals, and built some simple circuits following instructions (mostly dinky fuzzes, etc.).  Anyway, if anyone has any insight, I'd appreciate it.

Also...has anbody else noticed how crappy the pots in these things are?  I have a sneaky suspicion the "tweez" pot may be the culprit- the shaft seems wobbly, and sometimes adjusting that pot seems to help, though it's hard to tell...

[Processaurus]

could the mix pot be bad?