I think LBS staff generally appreciate regulars that know their stuff, and also spend $ there occasionally. They are also more willing to offer small or "easy" services or parts for free or reduced prices, especially if there are no other customers around!
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1989 Schwinn Paramount OS
1980 Mclean/Silk Hope Sport Touring
1983 Bianchi pista
1976 Fuji Feather track
1979 raleigh track
"I've consulted my sources and I'm pretty sure your derailleur does not exist"