I bought a secondhand MSD efi distributor recently, mostly since im on a budget but want decent parts. The guy said it had been in the motor a month, well it looks pretty chewed up round the collar! Anyhow first thing i did was turn the shaft over. I noticed the gear wasnt spinning true, slightly wonky infact. Im new to modifiying engines but common sense says to me i should be able to see any wonkyness in it. Am i right and if so is it knackered?!

If the gear looks like its wobbling, then it probably is. When you say chewed up, where do you mean? The flange that seats against the intake or the gear? Dont use it till you verify its good. Got pics?

The flange against the intake on one side, i guess where it was clamped and someone adjusted it, seems to have chewed it loads. But the real issue for me is the wonky gear, since the wear on it isnt even from side to side. I recon its 0.5mm outfrom square, is that going to cause problems?

Which side of the flange is chewed up (intake side, or top side)? if its the top i wouldn't worry about it as the hold down clamp is the only part that interfaces there.

This wonky gear business is strange, I've never seen a bent distributor shaft. If you can visually see the misalignment i wouldn't use it, if its out enough you could damage the cam gear. you could try removing the distributor gear and verifying that the shaft is actually bent, it could be just a poorly manufactured gear. In which case all you have to do is replace the gear.

-Zander