K2500 Velocity Issue on left/lower side of keybed with 2 adjacent Keys Not fixed after contact and board replacement

Synth Repair
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K2500xs–I have 2 keys that have an issue with velocity that does not appear to be mechanical.

2 notes (33/34)(F/F#) started having inconsistent velocity issues with the following symptoms:

  1. Play the note and velocity is normal.
  2. Play the note again, Within a few seconds (inconsistently), the note would show a velocity of 0, but would still be displayed via midi output, for example, and also displays on the test pages of the K2500 menus).
  3. I would continue to hit the note, at the same pressure (lightly), for about 10-15 seconds, and the note velocity would return to normal.
  4. What is happening is inconsistent - but fairly frequent less than a minute.
  5. The volocity tracking seems to be going away, and then coming back after a period of time that has nothing to do with how hard I hit the key.

Repairs to date include the following:

  1. A few months ago, while I had this problem, I ordered new key contacts from Syntaur, hoping it was dirty contacts. After replacing the contact strips with new contact strips, and cleaning the board, the problem remained.
  2. I was able to purchase a new contact board from Syntaur last week, but unfortunately, the problem with the 2 keys remains. The problem is the velocity drops to 0 at random times for about 20 seconds, then returns to normal.

Based on the randomness of the velocity dropouts, Im wondering if anyone has any suggestions or experience with a similar issue. I’ve replaced the contact strips and the contact board, and the velocity randomly drops to 0 for about 15 seconds. My DAW IS recognizing the midi notes when I hit the keys. It is also showing me the velocity, and I can see when it goes to 0, there’s no sound.

My setup includes a midi output to my computer DAW.

• K2500SX & Contemp and Orch Rom and Sample option

Any thoughts or advice appreciated. Im having a hard time finding the service manual, and will check that out, but hoping to get some advice. Im comfortable soldering, replacing caps, and those types of things. I also have a good test meter, and an ESR meter for inline cap testing.
I appreciate any advice.