@MattKing - From what i can tell the camera back is the original and totally windowless, i handle my film from it arriving in the post, to lightproof box, to fridge, to camera and to lab so unless someone has pulled ye old switcheroo tis definitely the same camera :|

@DWThomas Great minds thing alike and i decided to run some tmax through it recently and develop it myself as a control, the marks where still there but fewer and further between, a fact i attribute to my tendency to use B&W film in lower light situations.
I had the same theory about the film type reminder window so that too was taped over in the grand insulating tape test.
Similarly i had noticed they spring pin myself only recently when i removed the door to re-seal it, but surely andy light coming in through there would have been protected when i taped it up (or at least drastically reduced).

I replaced the mirror bumper foam along with the seals on the door but i will certainly check, first time in a long time my camera hasn't had a roll in it so i will take it to my room of light (the darkroom that with a flick of a carefully guarded switch becomes the intensity of a thousand suns for inspecting prints etc) and look at ever square mm of the body for anything out of the ordinary.

Not many people i know have an FD canon but there is a shop locally which sells pretty much every camera between 1920 to 1990 (its heaven) and im sure i could persuade them to let me borrow one for the day if i left my DSLR as collateral

@Polyglot/MattKing There is an LED based warning for under/over exposure and also a red glowing M for non Av , i wil check the curtain later today.

Thanks so much for all your help chaps summer is approaching and a non light tight camera seems somewhat of a paperweight