Paul Brush has revealed Lincoln failed in an attempt to bring former defender Ben Futcher back to the club from Bury.
The 29-year-old, who made 142 appearances for the Imps between 2002 and 2005, has featured just four times for the Shakers this season.
Lincoln are in the hunt for defensive reinforcements with Moses Swaibu, who is one booking away from a one-match suspension, and Adam Watts the club's only two fit centre-backs ahead of the league trip to Wycombe on Saturday.
"We would like to get an experienced defender into the club and Ben Futcher is one of a number of people that myself and (manager) Steve (Tilson) have talked about," Brush told the Lincolnshire Echo. "We made initial enquiries to Bury but were told he was not available."
Brush also denied that Lincoln have enquired about the availability of Notts County players Graeme Lee and Luke Rodgers.
The Imps assistant boss added: "We have not pursued Notts County about their players.
"We have made enquiries about other players but their clubs are not sure whether to let them out, what with the FA Cup coming up."