Several buttons on my VCI400 have stopped working. Some don't work at all or send any midi message, some you have to press really hard or several times. I opened up the face of the VCI to take a closer look, thinking I might be able to clean something, but it's just a simple button underneath, no dust or dirt and all looks normal, they seem to be hard connected to the circuit board. Wondering if anyone has had any experience repairing or replacing buttons on these at all.