As you say...........my reference to egg beater was just my description........definitely Shimano (didn't know that was a brand name.I assume the reference to egg beater just means the standard flip over two sided spd type pedal, rather than egg beater brand that are very different visually, and so I reckon the problem is that the original pedals may have been SPD-alike rather than SPD and though supposedly 'compatible' this 'shimano comaptible' bit is just the 2 bolt cleat mounting to fit SPD shoes, I had WMD? pedal/cleats and they worked fine together but a shimano pedal wouldn't take these cleats but a shimano cleat would fit the pedals albeit very BADLY so I wonder if one of the components is a copy?
I will check the other points tomorrow and confirm.