The Clarets slipped to a shock 2-1 home defeat to Oxford City in the Vanarama National League South on Saturday.
The result was even more remarkable because it was the FA Cup heroes’ first league success since the middle of August.
Stringer wasn’t happy that his team were the victim of Oxford’s only win for nearly three months.
He has seen his team fall off the pace and a third defeat on the spin leaves Chelmsford down in ninth - their lowest position of the season to date.
They face winless Whitehawk at Enclosed Ground this weekend and the manager knows they need to get back to winning ways - and that they must stop handing teams goals.
“We came up short and that’s a real disappointment,” said the Clarets manager.
“We had a lot of the ball, a lot of the chances but we didn’t finish them or keep theirs out at our end. It was frustrating.
“We’re still making mistakes and that’s what we need to work on to get things going again.”
Stringer added: “It’s a competitive league and we are know we have to be totally at it every game. It doesn’t matter who you’re playing.
“Teams are finding it too easy to get goals against us. We have to tighten up and get back to how it was a few weeks ago.
“There is still time but we need to go back to basics a little.”