Hotpoint WM63 continuously fills and leaks through door?

My Hotpoint WM63 has recently starter "sticking" mid-cycle. The control know seems to get stuck. It then stopped draining the water and wouldn't spin. I found the filter-pump, cleaned it (and removed 75p, several buttons and some nice shiny stickers from my kids pockets) and then ran an empty hot cycle. All was fine.
Four washes later and the control knob is "sticking" again. Latest thing to happen - machine running an "E" wash went into a continual filling mode, filled the drum completely and started leaking out of the bottom of the door. Twisted the controller to a spin cycle and managed to drain all the water out, but the spin cycle seemed to stick until I nudged the dial once more.
Any fault-finding tips/suggestions? I plan on removing all hoses again, etc. The controller board looks fine, no charring on any PCBs. All wires connected, drum turns normally by hand.
Could this be a load sensor issue? Trip to the launderette imminent - either that, or smelly kids...