I saw the other thread, and wondered why I'd not asked on here before!
I bought a toy for DS from Woolies about 5 years ago. It's about the size of an A4 bit of paper, and it's like an obstacle course for a ball bearing. There are levers at one end to control various bits of plastic (ie a magnetic arm that lifts the ball bearing)and you have to get the ball bearing from start to finish.
It wasn't dear - about £5 or 6. It could well have been Chad Valley. They don't have them in my Woollies any more
Any suggestions, so that I can Google it?