Thanks to all for the above comments - im glad this information has helped a few people and its great to read the feedback
Tim do you have any photos handy to post of the Metallica playfield you did for me? Tim's cost was more than reasonable and the result is staggering when you put it alongside the original. Honestly, if you have the chance to get something like a repro or replacement playfield cleared by HRP you will not be disappointed.
YES! That would actually be a great example - and i cant believe i didnt think of that
I will document that one here in a few days