Both Sunderland and Sheffield Wednesday have found a resilient Quakers tough to break down in the last week, and tomorrow evening Carlisle United visit The Northern Echo Arena.
Cooper does not expect to have added any fresh blood by then, but admits to being kept occupied by a series of calls from players' agents.
You have to give agents your time because you might end up with a player that turns out to be really good,
said Cooper, who has added a game at Gretna to Quakers' pre-season fixture list.
We're building a squad and trying to bring the right characters in which is important.
We need players that can blend into the changing room and can help the boys that are already here.
We've got some good players, we just want two, three or four to help them along.
Michael Brough is one of those already signed by Cooper and he has impressed in a midfield role against Sunderland and Wednesday.
Cooper added: He is ideal for us. He is a proper pro, he's a big lad, he's a good athlete and can play in a number of positions.
He can play in centre-midfield, centre-back or either full-back positions. It's important that we have two or three of them kind of players.
I tried to sign him when I was at Kettering because I've known for a long time what kind of player he is.
Darlington head to Gretna for their final pre-season friendly seven days before the Blue Square Bet Premier League kicks-off.
Taking place at Raydale Park on Saturday, August 7 (3pm), Gretna were established by a supporters trust after the original club were dissolved in 2008. They now compete in the East of Scotland League. Admission will be £4 adults and £2 concessions.
Kick-off for the friendly at Workington next Tuesday is now 7pm.
Remaining pre-season fixtures: Friday July 23: Carlisle Utd (H), 7.30pm Monday July 26: Whitley Bay (A), 7pm Tuesday July 27: Workington (A), 7pm Thursday July 29: Kendal (A), 7.30pm Saturday July 31: Billingham Synthonia (A), 3pm Monday August 2: Spennymoor Town (A) Wednesday August 4: Newton Aycliffe (A), 7.30pm Saturday August 7: Gretna (A), 3pm
Source: Northern Echo
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