i had the same problem here. it seems thats a classy occurence with the 8xx sonomat series :-(
i also used a 2 component araldite. the shaft of the operation knob was split in two so i first glued that together, using a clamp and let it harden over night. next day i removed the front panel (just the screw on the front and remove the knobs for volume, tone etc...) then you can remove the front cover easily.
i again used 2 component araldite, smeared the clue very generous around the center line and the shaft again, while i placed the front panel back onto its place the glue could dry a bit. that doesn't take more than a minute, which is perfect. then i "plugged" the operation knob back to the shaft and left it dry for another 24 hours. i never had any problems since. negative aspect is that this way you will not be able to remove the front panel again without force and damage the operation knob for sure. but i hope you will never be forced to remove the panel again. best luck
Reto Deflorin
September 2010