Winger Louis Briscoe has returned to One Call Stadium following a month-long loan at Nuneaton Town.
Due to injury, Briscoe featured just twice for Boro, who currently sit on the fringes of the Play-Off zone in the Skrill Premier.
The 25-year-old is expected to remain out of action for at least the next fortnight.
“Louis has had a problem with his medial knee ligament and he’s going to be out of action for at least the next two to two-and-a-half weeks,” said boss Paul Cox.
He continued: “As quick as we can get him back in our squad, the better.
“He’s a fabulous player and a goalscorer, and he’ll add to us at what I would call a really important time [of the season].
“We’re coming towards the busiest time of the year, building up towards the Christmas period, and we need as many people fit as we can.
“We need [players] not just fit, but also ‘chomping at the bit’ and as many of those as we can get, the better it is for the squad.”
Meanwhile, young centre-back Jason Gregory has also left the club by mutual consent.
“Jason has been a great kid to work with,” added Cox.
“Potentially I thought he was pushing on and he had a good loan spell at Rainworth, but the lad has decided he wants to look further afield in terms of his future.
“He’s looking to go into plastering and maybe playing part-time, so we wish him all the best.”