The Championship promotion-chasers were largely dominant during the opening 45 minutes and Agustien hit a 25-yard shot which was blocked by Orient defender TerrellForbes, before Sinclair went close again.
Moroccan striker Chamakh held his position to coolly side-foot the ball through the legs of TerrellForbes from eight yards out, right into the corner of the net, for his first goal since the end of November.