I agree that resale value isn't the all-exclusive factor when deciding whether to restore/refurbish. I enjoy doing it just to bring worn-out machines back from the "discard" pile.
The pedals are a great place to start. You'll get many different opinions on what to use for cleaning & lube. My favorite cleaning solvent is mineral spirits, because it does the job without noxious fumes or aggressive chemicals. That and a brass brush selection (for cleaning bare steel) from Harbor Freight go a long way. I also like to use Finish Line Ceramic grease on the bearings. It seems to seep out alot less when it gets warm/hot. Grade 25 lot-matched bearing balls are available from eBay or Amazon.
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"My only true wisdom is in knowing I have none" -Socrates