I stripped the play field, removed all posts, rails and mechanisms, lots of photos and labelling as I went. Anywhere the contact was lifting or dodgy I removed it and tried to trim it back to a natural line, I do not want to remove it everywhere as it is basically ok.  Removed all the loose and wrong coloured inserts and set about patching the wear areas.  I used K&H stop putty for the gouges to wood, it seems to work pretty well - easy to apply, dries quickly and can be sanded with a little block to make it flat.

Fortunately Flash is a popular machine and there is a play field decal for the common wear area and I bought this. It covers the whole circular bonus area, which was too much for me so after filling the play field I used some tracing paper to narrow down the area and then trimmed the decal down a bit. I was worried the dark colour of the putty may show through so I touched up the colour to try and match the general cream colour of the play field.  The decal lines up ok, probably stands out more in the pictures than to the eye. Time will tell if the ball deviates on the edge - with your finger you can feel a slight edge.  All up it looks a lot better than the bare wood that was present and hopefully no more wear will occur.