problems with Cort bass with active MarkBass preamp

[AxeAmpTN]

Hey y'all.  I hope someone here can help.

A customer brought me a Cort 5-string bass with active electronics.  He complained about the sound cutting out.  Sure enough, the sound would definitely cut out and the controls were very noisy with lots of static.  After checking all the solder joints, replacing the battery, etc., it still produced problems.  It seemed to me that the PC board was bad, so I discussed with the customer about replacing the circuit.

After researching it, this appears to be a MarkBass design made just for these Cort basses. The customer called the store about the problem and they sent him a replacement.  Actually, they just removed the controls and board from another bass and sent it in a ziploc baggie.  Classy.

I replaced it and everything seemed to work.  Then it started cutting out on the customer again.  This time, it appeared that the jack was not making a good connection with the plug.  After cleaning that up, the controls were making noise...the treble pot in particular was just noisy to the touch even with being grounded.  I just replaced the pot and now we're back to the same problems the customer had in the first place. 

I'm out of ideas here and frustrated as hell.  Who here has experience with this kind of thing?  Please help!

[shooter]

the PC board was bad

ya can't fix stupid no better than you can fix E-junk.  I would thank the coustomer, hand it back n DON'T look back