weird trouble with controller midi output

[mguidoux]

Hello guys,
I have a Evolution MK-461c controller keyboard, that I've been using for years with no issues with a Novation KS-Rack, and some other synth modules.
After a few months without using it I was going to practice with my band and I couldn't make the thing work. I tried using it with other equipment (Roland JV-880 and Kurzweil SP76) but it was useless. On the other hand if I disconnect the MK-461 and connect the kurzweil (with the same setup) to the module it works like charm.
I also tried to connect it to a Midisport 1x1 midi interface and the light that shows if midi data was being transferred never lit on.

The weirdest thing is, I took the MK-461c to a repair shop where they connected my controller keyboard to a Yamaha PSR keyboard and it worked with no issues at all.

I brought it back home and it still wouldn't work!

Does anyone have any idea what might be the issue?