sp250, midi out issues

[Shutoku]

As I scan this forum I see very few responses to topics, but I throw this out there anyway.
About a year ago I bought a Korg Kross, which I midi'd up to my sp250.
I also had the Kross connected to my mac via usb.

I noticed issues where I was holding a chord on the Kross with say an organ or other sustaining sound, and randomly the sound would drop out completely until I re-strike the chord. I was blaming the Kross.
Someone, either here or on keyboard corner, suggested it might be because of the usb. I disconnected the usb but the issue still occurred occasionaly.

A few months later I picked up a 4X1 midi merger which allowed me to use the Kross as a brain controlled from the sp250, my m1, and a yamaha KX5 keytar. As soon as I started using the merger, the dropping notes on the Kross stopped.

The only problem is that the merger gets power from one of the midi in's which I always had the sp250 in, and sometimes there would be no power unless I jiggled the midi cable from the sp250.
I figured maybe there was a bad solder or something so I took the sp250 into my korg repair guy (who is excellent) to replace it. He told me there was nothing physically wrong with the midi out, but I had him replace it anyway.
The problem was still there so then I thought it was a bad midi cable though I had used different ones over the months. It was not the midi cable, but none the less if the keyboards sat undisturbed there was generally not much problem.

This weekend I have a gig where I will only be using my Kross and the sp250, so for a week or so I plugged the midi out from the sp250 into the Kross. Lo and behold suddenly the Kross is dropping notes again!
So I switched out the sp250 for the m1 and there were no problems at all.
(In the end I"m going to just use the Kross with some splits and layers because I have to strike the stage fast for another band)

So this leads me to the conclusion that it is definitely the midi out of the sp250 causing the issue, and that it is not a physical issue, but a software/processor issue.

I don't imagine there is a cure, but I wonder if anyone else has had midi out problems with the sp250? It is rather disappointing, because I really cannot afford a new digital piano right now, though something lighter would be nice.