Thomson Monitor help needed

I have a Thomson CM36512 VI color monitor I use for my 800XL but the on/off button won't stay on? I must keep it depressed to have the monitor work. Once I let go it turns off. I have disassembled it and can't figure out if there is a quick fix? Ideas? Thanx.

Manual link:
http://www.bombjack.org/commodore/hardware/Thompson_Color_Monitor_CM-364512VI_Operating_Instructions.pdf