thanks boys, fixed it now, the angle on that piece is so tiny Id never have thought it made a difference but it does,
Actually I dont seem to have any trouble removing the playfield, now that I know its waiting to cascade all the moving parts onto the floor. By removing the coin feed tube then the kicker then the long bar and the two brackets I find I can remove and replace the play field quite easily without dislodging any of the parts. Its interesting that the brackets and bar need to be really quite tight to make the machine run at its best.
Im amazed at the condition of this machine, I know its not really old but the case is quite cheaply made and I expected some damage. All that was needed was a clean inside the glass and a couple of half inch re paints where the coins had hit the glass near the coin entry, then there was the usual arcade trade mark, white paint spatter on the top, so I did a light sand and re varnish the whole thing and it really is "as new". It even has it original lock and key and the original inspection card fixed on the inside case with its reg number. Not my usual thing but I really like it.