Help! Push/Pull knob staying in split position (Music man jp15)

[tronunator]

Hello!
I'm a very happy owner of a MM jp15 7 string.
Unfortunately, since some days the aforementioned knob is not working properly, that is, it stays in the split coil position.
I unscrewed the back plate, but I really don't want to unsolder stuff without knowing exactly what I'm doing.
It's not blatant there is something wrong from a first inspection.
Any chance I could fix it without replacing it completely?
Thanks for your help

 

[tronunator]

Okay after a little inspection I noticed a white plastic piece sticking out of in the backplate, which slightly moves into place when pushing/pulling the knob. I just took a plastic zip tie and tried to make it stiffer, it worked out. Of course not the most elegant solution, so if someone knows of a better way, don't hesitate to write it