Crossflow distributor cap wear

[tomtrout]

I'm running an Alden converted lucas 45d type dizzy on a 1700 xflow which is grinding away two terminals of the cap at an alarming rate. I fitted a new cap and within days it has virtually worn out two terminals. I've pulled the dizzy out thinking that the shaft must be p*issed but it seems to run true. The second cap was fitted true and square so I'm a bit lost. Anyone else been here?