Mellotronists

hi there everyone
i found this group after searching the web for anything to do with 
mellotrons and found a link here from ken leonards web site. thanks 
ken. (if youre here)
my name is pete dulcester and i live in the lake district in the north 
of england. im a kind of "jobbing musician", playing in a couple of 
bands here and there and generally making music my hobby for these 
last thirty years or so. my instrument of choice is the hammond c3 (i 
have 2 of them) and the fender rhodes of which i have three.
the reason ive joined in is because ive suddenly found myself owning a 
pair of quite large mellotrons. its a really long story how it got to 
this but the short story is that i was given them by a friend whose 
brother had died and whose house was needing cleared of his stuff. 
knowing i play music he handed me over these keyboards without knowing 
what they were. i knew about mellotrons from the old days but never 
expected to see one or play one. now i have 2!
ive looked all over the web for pictures and lt looks like i have a 
400 and a 5. the 400 is in quite clean nick but wont start up when i 
try it. there is a set of tapes in it and another set in a dirty flat 
black suitcase which i assume was built to carry them. comparing 
pictures and machine it looks like it is missing a drive belt and has 
a foot-shaped hole in the front panelling where it looks like someone 
lost his temper with it!
the 5 is in a worse state with the plastic covering peeling away from 
it and the wood from the casing warping. the 400 was stored in a 
cupboard but the 5 was stored in a covered outhouse that got damp. 
there are no tapes in the 5 and the metalwork looks either dirty or 
rusty.
so i have questions for you all. first how much effort would it be to 
renovate them? im thinking time and expense mainly even just 
approximately. the other question is whether or not they would be 
saleable in this current condition? are there mellotron breakers yards 
anywhere in the uk? (joke)
thanks for listening to a newcomer

pete