question about chroma dots/ missing episodes.

this is possibly the stupidest idea ever but, the chroma dots that have a colour picture incripted in black white film, the restoration team has software to retreave the chroma dots and restore the colour, but would chroma dots from missing episodes still exist on their tapes that were tapes over?

At a guess, probably not. From the description of the system posted on the restoration team site, I think the chroma dots have to be retrieved from video in fairly good shape - the source material has to be clean because the information is so faint. Even if it were possible to somehow pull the chroma dot information from a previously wiped tape, that only retrieves the chrominance (color) information; the luminance information (brightness/contrast/sharpness) would still be missing. The way that pre-DTV/pre-HD videotape works, the luma and chroma are encoded separately, and having only the chroma information wouldn't produce a watchable picture; in constrast (no pun intended), luma information only would simply give you a watchable B&W picture.