Manager Neil Baker made one change to his starting eleven with Harry Brazel making his first start in place of the unavailable Niall Maguire. New signing Andy McWilliams took a seat on the bench.
After a quiet opening the game erupted into life on 15 minutes when Rob Stevenson was brought down as he tried to go round Castle keeper Matt Johnson.
Dan Trickett-Smith took the penalty but he shot straight at Johnson who made a comfortable save.
Eight minutes later Mat Bailey was desperately unlucky to see his header from a corner crash against the crossbar and the ball was then hacked off the line in the ensuing scramble.
In the 35th minute Blues scored what turned out to be the only goal, Trickett-Smith whipped in a free-kick which Stevenson nodded deftly past Johnson.
Former Leek defender Sam Bradbury went close soon afterwards when his curling free-kick hit the outside of the post.
In a frantic spell just before the break Trickett-Smith was denied by Johnson's outstretched leg, Leek were denied a penalty when Stevenson appeared to have been brought down and Tim Grice and Niall Green both headed chances just over.
Blues should have been out of sight at the break and it proved a tougher second half with Castle looking to get an equaliser.
Danny Roberts got down well to make his first real save on 50 minutes, whilst Trickett-Smith also saw his low effort saved by Johnson.
Jordan Johnson came on in the 6th minute for Brazel and almost scored with his first touch when he nodded a cross just the wrong side of the post.
Charlie Walford had a long range low effort pushed away by Johnson and Grice appeared to be blatantly shoved over as he picked up the loose ball but the referee ignored strong claims for a penalty.
Stevenson has a shot well held in the 74th minute and ten minutes later he put a glorious chance over the bar after some excellent set-up play from Grice.
Grice himself put a looping header wide late-on, but Leek found themselves under severe pressure during five minutes of added time which ended with Roberts doing well to tip an effort onto the bar and over.
So, that's seven points out of nine for Baker's side, but they will know this win should have been more comfortable than it ultimately was.
Line-up:
1. Danny Roberts
2. Niall Green
3. Joe Kearns
4. Marc Grocott
5. Scott Lycett
6. Mat Bailey
7. Harry Brazel (14. Jordan Johnson, 65)
8. Charlie Walford
9. Tim Grice
10. Dan Trickett-Smith (15. Andy McWilliams, 78)
11. Rob Stevenson
Unused subs: 12, Zeph Thomas 16. Jessy Bavanganga, 17. Ben Chapman
Yellow cards: Marc Grocott, Charlie Walford
Man of the Match: Marc Grocott
Attendance: 248
# | Team | Pl | Pts |
1. | Atherton Collieries | 38 | 82 |
2. | Radcliffe FC | 38 | 75 |
3. | Leek Town | 38 | 74 |
4. | Colne | 38 | 73 |
5. | Ramsbottom United | 38 | 72 |
6. | Runcorn Linnets | 38 | 72 |
7. | Prescot Cables | 38 | 69 |