[Elecraft] Bizarre K2 keyer issue

[LL]

 This is the weirdest thing ever.

So my wonderful K2, #4442, was pressed into service once again, a few
months ago, after some needed TLC from Alan Wilcox.

All was fine. In fact, it was all wonderful!

So I just built a new antenna; got it up yesterday, it's a 40M full-wave
Delta Loop. Hoping for some DX.

Early last evening, I got some plugs on the end of the feedline, and
connected both antlers to the rig. After comparing received sigs, I decided
to call CQ, and compare RBN results. But someone replied, and I began a
QSO.

That's when this trouble began. I was unable to send intelligible code;
extra dits were being inserted. I tried changing menu settings, fiddled
with the key. I finally had to just bag the QSO and go QRT.

This never happened before. Whether operating, or in test mode, the keying
is intermittently whacky. It will sometimes send a couple or five extra
dits. In HAND mode, it will extend dahs, randomly.

As mentioned, this happens when transmitting, and it's the same when in
TEST mode, so it's not caused by RF.

I've tried a couple of different keys; same.

I tried to attach a brief vid showing persistent dits, but it didn't post
to the list. Let's try this: it's a brief vid of me sending
<https://www.dropbox.com/s/0pdb2m9pdpv2frp/20180827_194056.mp4?dl=0> CQ CQ
DE K3ESE K3ESE K - and the keying is correct. What comes out, not so much.

Any ideas...??

Lloyd, K3ESE