Criteria when restoring old sets

[SpacePolice89]

This discussion has come up in some other threads and I find the subject very interesting. What criteria do you have when restoring sets? When I buy old used sets (mainly from the mid 80s to mid 90s) I always try to buy sets that are described to be in good or excellent condition but sometimes for various reasons I buy sets that have missing pieces or have damaged pieces. For example if I buy a Futuron set from the 80s I try to keep the pieces as original as possible when replacing damaged or yellowed pieces. In most cases I have period correct replacements that I can use but sometimes I have to use a newer version of the same piece but I try to avoid that as much as possible. I never mix gray and bluish gray. I accept very little yellowing and scratches. Only if the yellowing is very minor I keep those pieces and I also replace pieces with visible scratches. I never throw away any pieces because of yellowing or scratches even if they are very yellowed or have major scratches or tooth marks, those pieces I use in non visible places in MOCs or inside mountains/hills when building landscapes. When I build MOCs or idea book builds for old themes I don't care if the pieces are new or old, I only try to stick to period correct pieces for official sets. When it comes to stickers (I hate stickers) I use original stickers if they are available and in good condition but that is seldom the case so most of the time I use replica stickers that look the same as the originals. I always want original instructions for my sets. What are your standards when restoring sets?  

[Feuer Zug]

With few exceptions, I haven't tried to restore old sets that I come across in bulk purchases. Those I do rebuild, I try to use period pieces (often from the same bulk purchase) to fill in the gaps. If they aren't there, then I go to my parts bins. Instructions are great, but I'm not buying old LEGO for the sets, just bulk parts.

[Stereo]

I only replace parts if they're functionally damaged (broken or deep toothmarks so they can't be built normally), yellowing and scratches don't really bother me.  I only try to match the era of parts if the set seems worth having 100%, a lot of the time I'm fine with building it 95% correct (eg. using a dark bluish grey BURP instead of dark grey, or 8x16 plate instead of baseplate) cause I just want to try the build, not mark it as a complete set in my collection.