Where to source a replacement zip from?
Anywhere that does alterations should have plenty. If you want a really good one then YKK are generally reckoned to be a good benchmark.
How to go about reproofing the flysheet and groundsheet
With the groundsheet, it ain't going to happen if you want genuinely waterproof. A new one will have molten PU added on at the material factory stage and you can't replicate that sort of thing at home. If you want something that's really waterproof then get it replaced. Scottish Mountain Gear are a good source for this, and are probably good people to talk to anyway about this particular project as it's a lot of their business so they'll know it better than most (certainly better than me!).
If the fly is canvas there are various re-proofers available that will do it, but for nylon it's again the case that its factory coatings that make a fly properly waterproof. An impregnating proofer will help "top up" the waterproofing and might be enough, Fabsil is the usual suspect.
How to get a new "A" frame joining piece?
If one from a Force 10 will fit then Vango can supply, otherwise check your local fabricators to see if they can cruft something together. SMG might have suggestions.
There comes a time when renovation is primarily for warm happy feelings more than practicality. Nothing wrong with that because warm happy feelings is what the whole outdoors game is about, but if you just want a working tent I'd look to get a newer one. You can get remarkably good things for very little money these days.
Pete.
