Thanks Pete,
Yes, the floor has a rebate which causes all sorts of problems when the cabinet is poorly handled etc.
From memory, I cleaned up what i could of the plywood - ran i nice neat bead, and squared the cabinet up. I also made new corner chocks which press inside the cabinet and hold the floor tight with the ply sides.
I do things a little differently now, but it was visually correct and proved a solid repair.
If you need any reference photos - just send me a PM and ill see what i can dig up...
Tim