Gall's parent club Carlisle had agreed for the attacking midfielder to remain at Vale Park for a further month but the discovery of a calf injury which could rule him out for up to three weeks has scuppered those plans.
Glover said in The Sentinel: "Hopefully Kevin will go back to Carlisle and get himself fit but I can't take a gamble on him if he's going to be out for between one and three weeks.
"He gave us another dimension in attack so I think we will need another body in for the run-in. We need a wide midfielder because we have enough options through the centre. It's now a case of ringing around our contacts and seeing what turns up."
But Glover will have his work cut out if he is to attract another player before Thursday's 5pm deadline.