The Shaymen remain in the play-off places but last weekend’s 4-1 reverse at Eastleigh together with a shock 3-1 loss at home to Altrincham a fortnight ago has dented what had been an impressive start to the season.
Halifax today host Kidderminster Harriers, who sit three places and a couple of points adrift of Halifax in the Conference table.
Aspin said: “First and foremost, we have to do better defensively. The manner of the goals we have conceded has been poor and we must stop the rot.
“Recently, we have not managed to function well as a team collectively. We need to improve in all aspects of our game, including in midfield and also up front.”
Marc Roberts is expected to return after serving a one-game ban for his red card in the 2-2 draw with Wrexham 11 days ago.
Aspin, whose side took just a point off the Harriers last season, added: “Marc is vital to us, no question. He has done tremendously well since coming to us and has improved vastly in his time here.
“He was a big miss for us (in the defeat to Eastleigh), and we are just glad to have him back.”
On the task facing his side at The Shay, Aspin said: “Kidderminster were our toughest opponents last year, and they were really impressive when we played them.
“They have just come back from 3-0 down away at Barnet (to draw 3-3) which is something that not many teams in this league would be able to do.
“Some of the players have not been performing to what they know they are capable of, and we will need to improve for this match.
“This is not the time to get on their backs, we will encourage them and they will improve.”