Ah - I'll try some +Rs then! I would have before but they seem to be stocked less and generally more expensive here in the UK for some reason.
Since my drive doesn't even function properly as a 411 I'm not sure how 811 firmware will help it but will give it a go if its still bad with the +R.
Thanks for replies. This forum is a fantastic resource - so much good solid info. You can learn just about everything you need by just lurking.